Personally, I block people who espouse things I believe are genuinely spiteful, hateful, or shitty. Generally, I use the block button to “curate” my experience with the intention that I can use Lemmy as brief escapism when I’m in the bathroom or on the train without having my mood affected by somebody posting something shitty.

I don’t block anyone for normal disagreements, because I’m a relatively normal adult and as such that sort of thing doesn’t bother me.