It baffles me as to why. I think it’s hilarious how Linus is so careful to not break user space (for good reason) and all the user space libraries break every week.
That's one of the attractions of Go, and to a lesser extent Rust; it's way less work than C to get a portable binary.
I think 90% of the problems I've encountered are due to glibc. They could easily fix all of them by adding a GCC flag that would allow you to compile against old glibc versions.
They'll never do that though because they are ideologically opposed to it.