Spaces become public through conflict.
It's the conflicts and how we are cooperating around and through it what could make the #fediverse meaningful on larger scales. Don't measure by "number of users", rather appreciate interactions and enjoy other's takes and life signs like you would do in real life.
Oh and protected spaces are totally ok.
There is no imperative to "open up" to toxicity. As they say, free speech does not mean everyone needs to listen.