a) most libraries are not UI frameworks undergoing significant perpetual rewrites (and a lot of the distaste towards those frameworks comes from the perpetual rewrites)

b) even given that, they share a mindset, and being able to talk about that mindset has value (trivial example: all the GTKs are GObject C libraries, Qt is a C++ thing.

You're right if and only if there is no transferable knowledge communicable by saying "GTK", regardless of version (or you're just not talking to anyone).