What you mean is: systemd could have fixed it, but it would have been a lot of work and a hack that wouldn't help you when efivarfs gets mounted on a sysv/upsta

What you mean is: systemd could have fixed it, but it would have been a lot of work and a hack that wouldn't help you when efivarfs gets mounted on a sysv/upstart/openrc system. The kernel was the best place for the fix.