Until this thread, there was no evidence that the backends were going to catch up. AFAICT setuptools had an ideological disagreement with that requirement, and so there was not “until backends catch up”, it was just going to be “relax requirements… forever”.
It’s still not clear that there is agreement from setuptools that they’re willing to implement normalization of filenames. At least one maintainer seems to still be hard against it in the issue tracker. Until that disagreement gets actually resolved It feels very much like relaxing PyPI’s requirement is just allowing the spec to continue to diverge from reality, and potentially makes a final resolution more complicated because it adds yet another axis of preexisting behavior to consider.
It’s hard for me to express just how little I care about what normalization requirements we have, I just want there to be an actual agreed upon spec that we can implement, and the reality of the situation is that setuptools is a large enough constituent that if they’re unwilling to implement something, then we can’t consider it an agreed upon spec.