Here's a deplatforming example that is very much in line with societal consensus: when Daech was recruiting teenagers and young adults from Europe, there was a constant struggle, by both platforms and law enforcement, to systematically de-platform the accounts pushing their propaganda.

It is likely that had this propaganda been allowed to run unchecked, there would have been even more people recruited by Daech to go fight in Syria (or get married off), and to attack random civilians in the name of this ideology. Most attacks, if not all, were perpetrated by people who had in large part radicalized online, away from extremist mosques where they might have been more easily detected.

That being said, I don't believe censorship or de-platforming should ever be used outside of preventing the spread of propaganda that results in actual attacks on people. Anything short of this is just talk.