This is mostly nonsense and FUD. We have virtualenvironments, requirements files, setup.py with extra_requires that can all be used to manage versions without relying on the particular packages installed on an OS. Most people contributing to open source would be familiar with at least some of these methods and if they are not it’s a good opportunity for learning.

And if they are not, then maintainers can pull, run black over the diff, and commit.

CI prevents poorly formatted code from entering main.

The actual changes between black versions of late have been minor at best. You’re making a mountain out of a molehill.

Having a tool that dictates formatting is a lot less oppressive to new developers than 100 comments nitpicking style choices.

since developing in python should be done in a virtual env to start with, I fail to see how this will be any problem. The pre-commit documented version of black will be installed in the venv of the project, problem solved.

I think you haven't understood what I've told you. Please look into pre-commit and using it.