Can you imagine what the #Fediverse would look like now if the response to Gab had been "Admins don't need to block these instances, individual users can just choose whether or not to apply a user-level block (mute) themselves"?
And #Meta is even more corrosive than Gab. Gab users just posted a barrage of hate and unpleasantness. Meta is commercially incentivised to destroy what some people are inviting it to into.