I don't think you're right about the starfishs migrating away. They're still on reddit, but now they're going to post all the same stuff everywhere else. Sure, they'll get banned, but they'll still manage to inconvenience other users who wouldn't even have to read their garbage if /fatpeoplehate/ and other containment boards were still around.
Gotta pick the lesser evil.
a lot of people are saying that getting rid of the containment boards is a bad thing, and while that is true to an extent
when it comes to hate-groups, they always gravitate towards each other and forming groups, because even if they're saying vile stuff, if they're just shouting it in a sea of people who aren't listening they aren't getting their attention fix. they need to band together and form coalitions.
i feel like when you get rid of /fatpeoplehate/, either a new containment board will show up, or the discussion just disappears.