I think you’re ignoring the social issue here, which is that we have never had any real success getting projects to publish binaries for anything other than full releases. We can talk all we like about “fast access streams” or “suitable for limited production use”, but ultimately I expect people to see “beta” and decide not to support that release or provide binaries.
Users have a lot of faith in Python’s compatibility story, but it’s intimately tied to the “full release” cycle. This proposal is, IMO, taking quite a risk by tampering with that perception. And yes, I know that “X.Y.Z is stable and follows the same backward compatibility as always”, but by encouraging people to use the betas because they are “stable enough” we’re creating a confusion where none existed before.