This is true, but also misleading: Homebrew did what every major "distro-level" package manager did, which was conform to PEP 668[1].

(This, as it turns out, was a great idea. A single global shared environment that pip used by default was one of the single greatest sources of user frustration in Python.)

[1]: https://peps.python.org/pep-0668/

No, pip itself did that, and fortunately. It’s a setting you can disable if you want to be able to accidentally trash your environment.

I want to purposefully trash my environment

Pip will let you! You just have to ask it nicely.