The problem is that most people using Python don't have enough expertise in C to do the same.
It also kinda destroys the argument that Python is good if your solution for performance is to use a different language alongside it.
But... the LSPs I've tried (and I've tried a bunch!) are all atrocious: false positives and false negatives galore. Perhaps I'm spoiled by LSPs from languages with better type systems. Our code is strewn with (to me) mysterious comments such as `# NOQA 1234` which my colleague uses to make his Python tooling work with the codebase. I'm used to languages like Elm or Gleam in which a LSP error means there is an actual problem with your code, and a lack of a LSP error means the code will compile and run.