Believing you are morally entitled to reply directly to someone because they speak in public is…definitely a position, I guess, but I think being able to specify how you want to be interacted with is deeply humane. (And being able to do it after a thread starts to go sour is so important.)
Someone will ask why blocking doesn’t make this unnecessary and the short answer is that prevention is better than picking off unwanted interactions one by one, and having to process each one as you do it.