You are assuming that our only options are "x86 hardware ring-0" or "Linux system call interface." Both are crufty in their own ways, but more importantly, neither of these was designed to be this. The right answer might be an interface that is designed with containerization in mind.
That was just a joke. I think haberman is spot on that both x86 and Unix are crufty in their own ways and thus cruftiness isn't a good metric to judge these abstractions on.