Does that help?
arguable.
BSD and commercial Unices used PCC and PCC derivitives for much of their history; by this token, GCC is the 'other woman', and this is itself ignoring the clear differences in philosophy between MIT/BSD and GPL licening
This is probably not true (because clang is in C++ it can't be less complicated than anything), and gcc is complicated in some parts because it uses much better algorithms (the LLVM register allocator is not as good as LRA). LLVM also has some very ugly DSLs like the .td files.
But GCC's codebase does have lots of added complexity from the extremely weird GNU coding style where they want you to pretend you're writing Lisp and all commits have to update a changelog file. Plus terrible GNU software like autotools and recursive make.