Linux (POSIX systems in general, really) userland syscalls are very stable even in non-LTS, this is as you point not the issue. However, that is only the interf

Linux (POSIX systems in general, really) userland syscalls are very stable even in non-LTS, this is as you point not the issue. However, that is only the interface to the userland - the "kernelland" driver/modules interface is not garanteed stable. This and LTS releases usually receiving important security backports reasonably quickly (compared to non-LTS versions) unless you somehow have certain expensive "Enterprise Linux" licenses and can coerce the licensor to do the backporting of the security fix for you.