I think the sane part of the software engineering world has realised that auto-formatting is just the right way to do it, and the people that disagree just haven't figured out that they're wrong yet.
Maybe you meant "why is Black specifically better than no autoformatting, given that it isn't perfectly stable across versions?" in which case the answer is:
a) In practice it is very stable. Minor changes are easily worth the benefits.
b) They have a stability guarantee of one calendar year which seems reasonable: https://black.readthedocs.io/en/stable/the_black_code_style/...
c) You can pin the version!!