If they do that, they have to be careful about countries that have data protection / privacy rights, and they might have to be careful about signing up companies/sites hosted in these countries, specifically, the EU

None of that is taking place. SSO and some deeper private discussion options will be available for paid customers. Those options are not relevant for the vast majority of people that would use moot though.

Absolutely not. We will never sell data and we hate ads.

In future we're going to charge for private posts.