Linux's ePBF has its issues, too.

I once was trying to set up a VPN that needed to adjust the TTL to keep its presence transparent, only to discover that I'd have to recompile the kernel to do so. How did packet filtering end up privileged, let alone running inside the kernel?

I recently started using SSHFS, which I can run as an unprivileged user, and suspending with a drive mounted reliably crashes the entire system. Back on the topic of swap space, any user that's in a cgroup, which is rarely the case, can also crash the system by allocating a bunch of RAM.

Linux is one of the most advanced operating systems in existence, with new capabilities regularly being added in, but it feels like it's skipped over several basics.