What do you mean? Glibc is well known for its commitment to compatibility. But that isn’t the issue: the issues are that there’s more than one libc, and that consumers actually want incompatible changes sometimes.

That's not usually the issue. Glibc is used by 90% of main distros, notable exception is alpine used in docker images.

The problem is Linux ecosystem's fixation on "build environment = runtime environment" idea, making it incredibly difficult to build against older versions of glibc (e.g. Ubuntu 22.04) if you're using something new such as latest Arch. This is not a problem on macOS, you can use an SDK for a particular OS version on any other recent version.