What made everybody move from a corporate social media platform to another corporate social media platform instead of the fediverse?
After all, the Fediverse and Activitypub is much more mature than Bluesky and the copycat AT protocol or Threads and … whatever they use.
This is the case right now.
There’s good reasons GMail doesn’t do that, but there’s absolutely nothing technical preventing from doing that, and I can’t think of anything that legally prevents them from doing that.
Not leagaly but users will be frustated and leave. They will rollback within a day so you will not need to worry too much.