The extremists types need to be controlled both online and in real world: the same way as you kick out THAT guy from a party who is trying to convince everybody for the 25th time that the earth is flat, the online platform would have to do the same. I had a few warnings on HN for the way some of my post were written and while initially not quite satisfied about it, I did reflect on it and it made me realise that these rules do make HN better.