You forgot muting...
with muting you likewise garuntee you never see them again. But it has some differences
1) less rude since it doesnt limit their ability to interact with people on your posts
2) less disruptive to people on your posts because it doesnt orphan tons of past threads that people left (people you arent blocking so why would you want to)
3) is transparent to the other party so causes less drama and less chance of them trolling you from sock puppets
4) Doesnt game the social system, in other words, when you block you game the dialogue, so people who see your posts see a false reality, the conversations arent an honest representation of peoples opinions. By not blocking people dont get echo chamber effects where they get a false view of reality and thus start to view reality incorrect.
Do you have hitler block? I dont think you do, you must be a hitler lover!
But yes, muting and filtering (depending on what service people are on) can be great tools for chiseling out the stream of the day, which might be different tomorrow or in an hour.