The Linux userspace ABI is actually quite stable and rarely changes. If this wasn't true, every time you installed a new kernel you'd have to upgrade / reinstall everything else, including the C compiler, glibc, etc. This does not happen.

The Linux kernel ABI (kernel modules, like device drivers) on the other hand, is unstable and closely tied to the kernel version. Most people do not write kernel modules, so generally not an issue. (I did, many years ago.)