They are ad financed, clickbait driven "engangement" machines, that are designed to make people addictive and do not respect their users at all.

So TikTok for scientific papers already makes me not want to engage with the concept. But a social network with a focus on science is something I am interested. But the base would need to be solid. Where I can trust that they do not sell out to some ad network in 2 months after they established some users.

Because you don’t control the existing social network, meaning you can’t exploit and profit from the users in a group¹, which is the whole point of making a digital social networks².

¹ And if you do find a way, the parent network will simply eat you up.

² Outside of a few truly ideological non-profits.