I wouldn't describe the FSF's position that way (they value Free Software for its own sake, and their goal is that all software should be Free Software), but even if that were their position, I'm arguing that their handling of GCC and refusal to support it as a library directly motivated the creation of LLVM and led to a scenario that better supports the creation of proprietary software.

Providing a GCC library would have significantly lessened the motivation for LLVM: many of the "we need a library" folks would have one, leaving just the "we need a permissively-licensed library" folks, and the "GCC's codebase is awful" folks. (And even some of the latter group might have worked to fix GCC.)

That's not the only thing done wrong with GCC development. The much worse problem is that GCC doesn't really support reviewing and accepting patches; you pretty much have to have commit access to do any significant work on GCC.