Earlier quoted context omitted.
But the licensing didn't change between gcc 12 and gcc 16, so that doesn't seem like a good explanation?
It is not a good explanation because that is not the reason. That reason is for Mac OS. I don't know the details, but BSDs normally modify the GCC version they use. IIRC OpenBSD used to use GCC 2.95 for years. Porting NetBSD base to compile with a newer GCC version is not as simple as a version bump. My guess is that they haven't prioritized that work yet. Patches welcome!
2.95.3 and 3.3.6, both have now been retired in favour of gcc4. The majority use clang now, though.