If there was a social media network that could exclude these things, then smaller would be fine.

I remember Google Reader as a brief, well-balanced example of healthy social media platform. It was mostly text, the selection bias was in favor of users who were savvy enough to understand RSS, generally interested in an array of different things, no engagement algorithms. The blogosphere that drove much of the content at the time was wonkish, (more) independent, often irreverent but also sincere about what a better future for human civilization and politics could be like. Haven't seen another thing like it since.