While it would be nice for the kernel to handle any kind of bad behaviour by default, it isn't always realistic.
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.
Please see my response to tdsamardzhiev. I have replied to some of your points there. I agree this borders on bad behaviour since the author knows the kernel does not have rate limiting in place. Ideally he should have put in a feature request with the kernel devs and should have self regulated the log traffic using some workaround (like checking for debug.systemd) until the kernel stepped up its game. If I were Linus I would have taken this up as a challenge (as I am sure he will too).
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.