It's a shame how the core maintainers see CPython as a "reference implementation", rather than an opportunity to make a world-class programming language implementation. That the CPython maintainers have, time and time again, decided for a "simple implementation" has pushed away many professional VM engineers and researchers who would be more than willing to help maintain a JIT.

I also will say that a lot of the complexity of making a Python JIT is all the weird edge cases and special interpreter functionality. To a VM engineer, CPython is a very bizarre codebase; all the complexity is tucked away in corners other than its C codebase.

Your complexity has to go somewhere.