Almost every social media platform now has its own video hosting service, and that is the service privileged with automatic-playing or otherwise friction-free playing video content. As a result, on, say, Twitter or Facebook, the videos that get the most virality are the ones being hosted natively on that social network's corresponding video platform.

I agree with you that it would be better if everyone self-hosted and was able to charge what they wanted. I think it may be more realistic to hope for more platforms—competing with each other—to whittle down the rent they are able to seek from the creators that bring them value. Make them compete for the content creators. And, if they grow too unwieldy, regulate them (or threaten to) so that they set reasonable ground rules.