The other practical solution from "host yourself" is "maintain, in the long-term, multiple email accounts with multiple providers" so the blast radius of running afoul of one of these providers is curtailed. Fine advice, but in practice few people are willing to shoulder the inconvenience of doing it (and the bookkeeping to preserve it).

Ironically, this is one of those places where in the US, government intervention could help... Not with regulation, but with service provision. A ".citizen.us" account provided through a federal bureau could be constrained legally in ways that a private email account currently cannot and serve as an authorization provider for citizens who don't want to entrust their digital identity to a megacorporation.