Which is the optimal split! Write application/composing code in Python and highly performance sensitive parts in some FFI language (nowadays probably Rust?). It's not great if you do performance sensitive stuff all the time, but amazing if you just want to build something.
I understand and somehow agree with your point, however, it would also be nice for someone to have the ability to build something performant with a language like Python. But this is not really possible today, so the narrative that Python is for prototyping will keep holding.
