I'm not sure about the exact conclusion you seem to draw but it seems to be something like "GPL projects tend to have better outcomes than non-GPL". The whole point of the thread doesn't support that conclusion coming directly from the GCC brain trust. It's only natural that niche GCC users are going to hang around the longest.

I'd also like to note LLVM/clang didn't gain large non-apple marketshare until GCC adopted GPLv3 which has more to with it's stagnation than anything IMO. v2 is palatable to many business needs, v3 is not.