gzip is a pretty old, pretty core program, so I imagine it's largely in maintenance mode, and that there is a lot of friction to pushing large changes into it.

gzip is a pretty old, pretty core program, so I imagine it's largely in maintenance mode, and that there is a lot of friction to pushing large changes into it. At one point, pigz required the pthreads library to build. If it still does, the gzip people would need to consider if that was appropriate for them, and if not, rewrite it to be buildable without it. There are multiple implementations of zlib that are faster than the one that ships with GNU gzip, and yet they haven't been incorporated. There are also just better algorithms if compatibility with gzip isn't needed. zstd, for example, supports parallel compression, and is both faster and compresses better than gzip.