Python is my favorite language, but I have fully embraced uv. It’s so easy, and so fast, that there is nothing else remotely close.

Need modern Python on an ancient server running with EOL’d distro that no one will touch for fear of breaking everything? uv.

Need a dependency or two for a small script, and don’t want to hassle with packaging to share it? uv.

That said, I do somewhat agree with your take on extensions. I have a side project I’ve been working on for some years, which started as pure Python. I used it as a way to teach myself Python’s slow spots, and how to work around them. Then I started writing the more intensive parts in C, and used ctypes to interface. Then I rewrote them using the Python API. I eventually wrote so much of it in C that I asked myself why I didn’t just write all of it in C, to which my answer was “because I’m not good enough at C to trust myself to not blow it up,” so now I’m slowly rewriting it in Rust, mostly to learn Rust. That was a long-winded way to say that I think if your external library functions start eclipsing the core Python code, that’s probably a sign you should write the entire thing in the other language.