There exist alternatives: the Mastodon federation network and alt-right clone gab.ai.

The problem with letting people do what they want is that this was and will be abused for propaganda that sabotages elections - for example spreading lies about who is eligible to vote or that vote by mail is ripe for fraud.

Multiple platforms of this kind exist. And I'm glad they exist. But there's obviously a reason no one of them becomes mega-popular. This paradox is the biggest obstacle for the practical free speech argument (as opposed to the legal one).