I mean, it would be nice if the kernel by default could handle a simple forkbomb, but it doesn't without restricting your limits.conf fairly severely. You can blow up the system in a variety of ways that are outside of the kernel's responsibility. It's not up to the kernel devs to hack around your bad behaviour.

While systemd is obviously doing something stupid, no userspace program should be able to dump so much to the log that the machine becomes unusable. It seems like they were going to apply per-file descriptor limiting the way to they seem to limit in kernel logs on a per-log site basis.