The invite only access puts the owness on the operator of the platform instance to be responsible for what's shared there.
It's designed for people that already know each other who need a private space, not a large platform for anybody.
There is also some built in protection for when someone new is invited to the server. Each member needs to allow that new member access. The idea is that I, the server operator may have welcomed someone to the community, but a server member may not feel the same way, so their content is not shared with that new member until they decide too.
That's an interesting model. It sounds closer to a private club than a traditional social network, where trust is negotiated by the community rather than just the administrator.
It's designed for people that already know each other who need a private space, not a large platform for anybody.
There is also some built in protection for when someone new is invited to the server. Each member needs to allow that new member access. The idea is that I, the server operator may have welcomed someone to the community, but a server member may not feel the same way, so their content is not shared with that new member until they decide too.