On 4chan people refer to “containment” boards for topics that are racist, inflammatory, or regularly derail conversations (ex. pol, b, mlp). That way the people who want that aren’t always polluting boards where people just want to talk about (for example) food or technology.
So I was half joking that hexbear is like a containment board. It isn’t quite the same, but since other Lemmy instances can block hexbear all at once it has the same effect.