Well let’s say someone just spams a prominent account with bot accounts, such that any and all discussion beneath their posts is ruined. Or fills the mentions with slander, hateful comments etc.

twitter is the Wild West right now, full of bots and comments that violate rules but take a while to get enforced.

Blocks solve that. But also deprive people of being able to hear announcements.

Splitting the ability to listen to a broadcast and the ability to broadcast on a broadcast seems sensible. You could, after all, be removed from a courtroom or government press conference for being disruptive.