Have yet to personally block any instances. So far I think the closest I've come is blocking a spider community because fuck those hell spawns and a Minecraft community or two.

Edit:

Found out there's more than I remember being blocked. Multiple mc communities, a cock community (, because that stuff ain't for me and I remember accidentally clicking on one post from there by accident), a pussy community because I don't come here for porn, a Sintendo community, some bikinibottomtwitter or something similarly named community (you can guess why), and for some reason an xbox community (couldn't tell you why).

Also, I noticed for some reason I have someone from a different instance that I cannot remember why I blocked. Some guy from lemmt(dot)tf, so I have absolutely no clue since I have no idea what that instance is like, let alone remember anything about that account.