@Anri as my limited knowledge to XBO development results, there was a break in Microsoft's politics to open their XBO market for indie games and small sized people a while ago

@Pascua2019 The point here is that vendors of those systems have at one side invested a lot of money and time to research for the technology and it's OS, on the other side keeping the cost as low as possible to get a whole market to buy their product. Nintendo has had more innovations in past years while Sony has had better games and (this is a point of personal oppinion) more performance than similar console generations of Nintendo and MS.

The performance point is the difference in writing games for PC or Console. Normally a console has a single locked thread to run the OS on and other threads that are reserved for the software a user is actively using. Normally no scheduling happens here while on PC you have hundrets of services running in background and multiple programs a user launched that each need it's time and space to run on a limited core CPU. This is why the OS on a PC schedules tasks certain ammount of execution time. Consoles this way need less hardware power and so keep the price in a range that nearly everyone could buy a console against a PC of 4 or 5 times the price.

See Sony's PS VR in opposite to Occulus for example.

Another point is that every player wants (if he/she really needs is another question) social environments like in-game firends, messaging and also a store to lazily grab his games from including payment information. This shows a kind of security issue when the COS would be open for anyone, grabbing those information or even the whole money of a person just by putting a game with some spy software onto a user's maschine would be quite easy. That's why vendors provide SDKs and resources to verified developers only and software is encrypted and digitial signed by Sony before it can execute on Playstation or Nintentdo or whatever vendor you like to place here.

I've developed some games for PS and also the old NDS devices. A runtime based language like C# or Java would be very slow and insecure on the hardware so the way to go is C++ with access to some STL implementations made by Sony or Nintendo themself and anything else needs to drive the provided SDKs. They include code to access hardware level features like Atomics, grab Input or establish Network Play for your game.

And the point why it is that limited to get resources is the verification process. You need to have an established company, buy special versions of the hardware made for especially development (driving less security features so you could for example debugg your code) for multiple thousands of $ and at the end get your product reviewed to the guidelines of Sony or Nintendo before accomblish to sales. This is a process of spending a lot of time and money you need to get back during sale so no one will post ressources outside of the community of verified devs. I believe this is also against the guidelines of Sony and Nintendo and you could get banned from dev-program for that

17 hours ago, Pascua2019 said:

Something like the iOS that have both Quality Control and Open Platform Development.

iOS doesn't really have much quality control over their apps. It's all about the numbers. And the public opinion of the AppStore is that it's 99% worthless junk. Even more so on the Android store, which is arguably even more open to developers than the AppStore. Since Steam started allowing any game on it, people have been complaining that it's being "flooded with junk". See a pattern there? No console wants to be known as the "junk games" system, that's why the certification process exists, and console manufacturers curate which games to allow.

16 hours ago, Anri said:

I've been living under a rock!

A "Developer mode" for the XBox One?  ?

Before I rush out and buy a second XBO purely for development...whats the catch?

https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/

Reverse the perspective for a moment.

You are a hardware manufacturer and game publisher. You have a premium product, what you consider to be the best in the world. You have developers lined up to use your product. Not just any developers, you have the best and the brightest, the biggest companies, all willing to pay you in order to develop products on your system, and then pay you more for every product sold.

It makes some sense to open it up to people who have some experience developing products elsewhere. After all, if you can get these people who are already making games on their own, you might be fortunate to get people before they make exclusives for other platforms. Of course, the group collectively also produces lower-quality products. Since you don't want your high quality premium product to be associated with low-quality goods, you can use your certification process to ensure they meet the quality standards.

But why on earth would you open your premium product to anybody? In particular, the "anybody" who are absolute beginners, who collectively don't even know what they are doing, who have no skills and are statistically worse than the lottery when it comes to making money.  That group has a demonstrated history of publishing bad goods, a demonstrated history of giving companies bad names.

Look at Microsoft, and how they were burned on that.  Microsoft had been bitten badly on the topic with DOS and again with Windows, they learned their lesson before entering the game console arena.  Anybody could create device drivers and add-ons, and 'anybody' frequently did.  When systems would crash people would blame Microsoft and blame Windows, but in fact Windows wasn't the problem, it was the shoddy third-party drivers and programs. It took Microsoft over three decades to shake free from that, eventually introducing enormous barriers between customers and the ability to install drivers from third parties, big scary warnings to users before they installed them, plus modifying how crashes were handled to ensure that Microsoft and Windows were clearly not the product at fault, but even still today when shoddy third-party programs crash on Windows people still blame Microsoft and Windows for the crash after they've done everything possible to stop it. They don't want that to carry on to video games.

Sony's video games division started out, and remains today, a small portion of their business. They know full well from their big product lines how effective shoddy merchandise is used to break into markets, and how damaging shoddy merchandise can be to their brand even when their product is amazing and the shoddy competitor is the the problem. and they've been fighting it since the 1950s. Inferior brands of transistor radios in the 1960s meant people would blame the highly popular Sony models even though Sony had nothing to do with them. Inferior Walkman knock-offs in the 1970s and 80s meant people would complain about Walkman products even though the defective product was a cheap competitor. Repeat again with inferior CD players after Sony worked so hard to develop the format with their partner Philips. Inferior knock-offs and components in semiconductors, in televisions, in so many products. Piracy in their Sony Music and Sony Pictures divisions. Sony has spent nearly 70 years living what happens when they release the world's best premium product in a marketplace only to be devalued due to completely unrelated shoddy third-party products and knock-offs. Twice they nearly collapsed to bankruptcy due to the problem. Even though the company has diversified a hundred times over and games only make up about 5% of their business, they will fight with every tool they've got to ensure their premium products and premium brand is protected against any external entity.

Nintendo learned their lesson the first time from Atari and Coleco's Telestar in the 1970s. Their Color TV-Game wasn't the most popular of the era but still sold millions of them and saw what happened when their competitors had unauthorized cartridges. Nintendo learned the lesson again with the NES and used lawsuits effectively to prevent people from tarnishing their brand. They never forgot the lesson, and won't let their name be tarnished that way again.

The door is open wide to anybody who can (1) create a high quality game, and (2) bring the resources to bring a high-quality game to market.  If someone comes to them wanting to be a potential business partner and isn't able to create (or can't be bothered to make) their own high quality product to contribute, why should the company partner up with them?

If the game developer can create a high quality game then they're welcome to partner up. Because in that case Sony, Microsoft, and Nintendo do see the potential for a good business partnership.  Even if the game is not world-class quality, it can add value.  But if the game developer has nothing they can contribute, the console company has nothing to gain and everything to lose by partnering with that developer.