I tried asking questions on other websites on what tools/books I should learn to get the job done, and I was asking for advice to see if there's a more efficient way to creating my game, such as if one language makes things more efficient. (In terms of less bugs, runs faster or w.e else an educated person would know about.)
For a beginner, this question is basically meaningless. The sorts of issues you're describing just won't come up until you're far more experienced. For example, C++ has an internet reputation as one of the "faster" languages, and while that may be true in some circumstances you won't be dealing with a code scenario where that will come up for a long time, nor will you be able to take advantage of what C++ offers in that dimension. By far the best answer for someone starting out is what you describe-- you just need to pick one and get working.
Is game development really that simple as, I read a book on a language and I get straight to making my ideal game just like that?
It's that simple in the sense that coronary bypass surgery is just removing a clogged tube and replacing it with another tube. Actually doing it is harder than that description may suggest.
If I take peoples advice I might run into a problem that might make me scrap my whole game or remake everything all over again because of a single issue.
You might run into a crippling problem no matter what you do. If you could predict that sort of thing right now you wouldn't be a beginner. In ten years' time you might be able to make very good, nuanced choices about this sort of thing, but you'll develop that skill as a result of overcoming challenges between then and now. There is no path to programming games that is straightforward, easy, and has no risks of issues down the line.
Is it really a bad idea for me to post my game idea, then ask people what languages/tools they recommend I learn about to get the job done?
Because I asked this question on many sites and never had a single suggestion.
The real answer is the same as what you say you've gotten elsewhere-- it doesn't matter much what you choose, because most languages can do what you want. If you just have to have a specific answer before starting, then stick with Ruby because you already have some experience working with it. I promise you, any choice you make will still leave you with issues you didn't predict, and you will be able to address them.
As has been said above, it's easy for a beginner project to get out of hand in terms of complexity. Before diving into a multiplayer networked game, you may want to focus on something smaller. You could try coding a couple of sample characters, a couple of rooms/dungeon areas for them to explore, something like that. It's still plenty of work, but it's a realistic task and you can build on it for the future.
I also recommend not starting with your dream project because beginners are very likely to 1.) imagine something way beyond their ability to create right away, 2.) produce incomplete or problematic game designs which are very difficult to implement in code (whatever the language and tools being used), and 3.) focus on the "fun" game elements and neglect the utilitarian aspects of the program which must exist but are dull to create and debug. A smaller project that isn't as close to your heart will be easier to create, less frustrating, and ultimately bring you closer to what you'd like to accomplish.