In the end you end up with the same problem. All the "exterminate the jews" types go to the free speech platforms at which point everyone else leaves, even if the people with the ideas that aren't liked are using respectful language. It's not just the bad faith and trolling that make people want to leave the site, it's the base level ideas of the people who have been moderated off other platforms.
> The moral of the story is: if you’re against witch-hunts, and you promise to found your own little utopian community where witch-hunts will never happen, your new society will end up consisting of approximately three principled civil libertarians and seven zillion witches. It will be a terrible place to live even if witch-hunts are genuinely wrong.
I think that a platform where people expect the ugly ideas to be debated (in good faith) will have the users that are willing to do that[1].
Not every platform needs to have _all_ the users. I know that it's a bit of an anathema on a discussion board built by venture capitalists to say that the goal of a social platform should not be to maximize the amount of users and engagement, but here we are. I think optimizing your service for "everyone" is a bad strategy in competing with existing social networks, especially coming from an "indie" background. Not that Parler is exactly indie.
[1] I'm saying this as someone that is working towards a discussion platform that targets smallish to medium communities formed around a common interest. In this world if moms wanting to share their latest knitting project are excluded from a service that targets free speech people, that's fine, there can be a knitting community out there also for them. Having these two communities intermingle by using something like ActivityPub is a way to keep "the network effect" but keep them separate enough.
> I think that a platform where people expect the ugly ideas to be debated (in good faith) will have the users that are willing to do that[1].
This does not actually...happen. At least not over the medium and long term. What actually happens, and you can see this in practice, is that decent people are not particularly interested, over long periods of time, in arguing that no, there is no globalist (read: Jewish) conspiracy to take over the world. They lose interest almost immediately, while the frothers intellectually crossbreed and turn from one particular flavor of bigot into all the flavors of bigot.
The problem isn't, as you are characterizing, that a platform must have "all the users". The problem is that this strategy hyperconcentrates relatively anodyne conservatives into literal-not-figurative fascists, and has been doing so for quite a while. The active creation of intellectual cul-de-sacs, of epistemic closures for hateful beliefs, is a major factor in why we're where we are right now.
I disagree with you. I think that the phenomenon that you described (which exists on most social platforms that are advertising themselves as "free speech") is not present everywhere and my impression is that the problem is exactly with the "chase all the users" mentality.
One example that I can think of the top of my head is Scott Alexander's blog, where I saw opinions put forward (most of the times in a respectful manner) that ranged from extremely egalitarian to extremely libertarian. I am entirely sure that some of the people posting there have views that veer into "one flavour of bigot" or another, but because the community as a whole would rise against the most objectionable types of ideas that one could put forward, they never do it. To me that is a healthy community and I hope it can be achieved in other places without needing an "alpha-personality" at the center for people to gather around.
