No, that is rather a Solaris quirk. That's ancient (literally) sysv behavior and killall in neither OpenBSD, nor FreeBSD work like that today. So in practice,

No, that is rather a Solaris quirk. That's ancient (literally) sysv behavior and killall in neither OpenBSD, nor FreeBSD work like that today. So in practice, what you're saying isn't relevant to majority of *nix users today.