No the difference is that GNOME is moving towards a 'product'. Everything is designed to work together, to be consistent everywhere. When you mix and match, you just get medicority because none of them were designed to work together at all. I would not call that even a Unix philosophy, it's just something that happened organically.

Doing what GNOME is doing is hard. Making hard choices on what to keep and what not. Fixing the things in the other parts of the stack instead of band aiding it in their own.