> why not just use the existing social networks?

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.

> ² Outside of a few truly ideological non-profits.

So the question stays the same: why is this not just a Mastodon server?