I understand where you're coming from, but what you're describing is why they don't want or have to, not why they can't, which is specifically what I'm focused on as I think we otherwise just take these being the same thing as a baseline assumption, which is obviously not the case.

We need to be clear that this isn't a technical limitation on the part of these companies, and them choosing to pursue this modus operandi is purely for their own convenience at the cost of the user.