The common excuse is indeed wrong, as pypy proved. IMO the real issue is the python C API.

The python C API is the "killer app" of python, and what gave its edge against otherwise similar languages (ruby/js). That's makes it unique (the whole scientific stack). But a lot of early choices leaked into this API, and this (+ preference from guido for simple implementation) is at odds with doing JIT: lots of global state (instead of explicitly passing interpreter state), ref counting, no tagged pointers meaning boxing/unboxing everywhere, etc. Some of those are getting gradually fixed, but that's a slog, though maybe AI can accelerate a lot.

I had high hopes for HPy but that unfortunately fizzled out.