I never said they couldn't I said they couldn't without worrying about legal repercussions. Even in the cases when they're in the right, they have to carefully worry about the license. If I develop on an opensource stack, its prohibitively expensive to deal with the overhead of fixing the underlying components rather than put workarounds in my code. Even if the former would benefit everyone the most.
I read your comment a couple of times and I must admit that I just don't get what you're trying to say. As I said before, the developers don't have to worry about legal repercussions unless they intend to distribute the modified code under a license which would violate the terms and conditions of GPL.
So if you're developing an open source stack for your own personal needs, modify the underlying components any way you want to. If you want to redistribute it, though, you have to give the users of your software the same rights that you were given when you used those components. It's as simple as that.
