That's the thing, you don't have to :) While I think uv is a great tool and highly recommend it, you are more than welcome to use any of the other build backends or package management tools that fit your workstyle. By having these packaging PEPs (amongst) others, the ecosystem has been able to try out different approaches and most likely over time will consolidate on specific ones that work better than the others.

Anecdata, but uv served as a very good packaging mechanism for a Python library I had to throw on an in extremis box, one that is not connected to the Internet in any way, and one where messing with the system Python was verboten and Docker was a four-letter word.