I can just as well claim that ignoring startup with a small hot loop would unfairly favor a JIT compiler, since it ignores problems that would crop up in real w

I can just as well claim that ignoring startup with a small hot loop would unfairly favor a JIT compiler, since it ignores problems that would crop up in real world scenarios such as poor code locality. Basically what you're suggesting would be the absolute best-case for JIT.