Why? There are a lot of products where fixed price offerings can exist, like internet access in many parts of the world. The way that Anthropic implemented this change and how they explain it, hints that this could work very much the same: There is be a level of borderline abusers that need to be reigned in. The rest are a few power users that are subsidized by a lot of normal users.

I am not saying this is what must happen here, but I see no effort to substantiate why it could not.