Not everyone thinks we should be free to spread hate. Germany has good historical reasons to ban holocaust denial. Rawanda has good reasons to ban genocidal speech. No more going on the radio to say, "Cut down the tall trees".

The reason to not platform hate speech is the same reason you're not allowed to yell fire in a theater or bomb in an airport without their being one. Or say you're going to kill the president. Even the US has limits on what can be said, including liability laws. You can't just defame your neighbor and not face legal repercussions if they take you to court.

One can imagine this argument during the Salem Witch trials. "She's a witch" wasn't just a joke back then. It could get someone burned at the stake.

The US has good historical reasons to ban the promotion of socialist/communist ideology, yet I don't think many people on the left would be down with that.