I think the thing is that it's very rare for an idea to be directly translated into a product in it's original form. There are changes and refinements along the way, and it's not unusual for the idea to be changed quite a bit from the original thought during the process, especially when iterative development techniques are used.

Rather than starting out as definitely good, definitely bad, or definitely average, most ideas are potentially good, and what happens to them after conception can result in either an excellent, a good-but-not-exceptional, or a bad product.

I also think this concept of a unique, non-derivative idea is an exceptionally rare thing, or perhaps something that doesn't really exist at all. Creators may not always intentionally use a derivative process to create their ideas, but once you can see the idea you can generally always describe it as "this existing idea, but with these changes", or "this existing idea, without this", or perhaps "these two existing ideas combined". Building on previous work is a good thing, and whilst it's also good to break the mould a bit with something new and less derivative, the foundations in existing products and ideas is almost always there.

Ideas may be dime a dozen but good ones are not

That's another one I see pretty frequently but which doesn't seem to actually be backed up by much actual evidence. There are loads of really good ideas out there presented by people with no ability to actually implement them, and many of the lesser ideas could easily be refined into good ideas in the hands of people with a good understanding of practical limitations.

Sure, you absolutely need an idea to produce a good product, and some ideas are better than others, but in the end there are a huge wealth of ideas -- most of them with plenty of potential -- floating around out there, and it's only those who are able to successfully execute them who bring quality products to market.

We may be seeing this frequently probably partly due to Dunning-Krugerish effect leading us to see no one saying "This is my terrible/mediocre idea, but I will stick to it".

Btw, not sure of page but we are on the same chapter at least, by saying good idea, I refer to business, limitations etc aspects as well. More you know and are aware, less D-K effect and delusion involves.

So, "Ideas are dime a dozen" sounds like coal and diamond are same when in the soil (carbon) , but you can polish diamond easier when its in your hands. And also there is no need to shout "hey , look a diamond" before somehow closing :) Not every ideas have high entrance barriers keeping other out or amazing USPs.