There's this notion of 'bad money chases out the good'; stems from the time when coinage was made from expensive rare metals. Because weighing your currency is annoying, the state decrees that any stamped coin is to be treated as if it is worth precisely what it says its worth, even if it is a little light.
In such scenarios, everyone saves up their fat coins and spends their most shaved off misshapen light coins. Eventually ALL the money in circulation is the 'bad' money.
The same seems to happen with social networks: _IF_ you allow questionable stuff on your site, soon all the other users will go elsewhere, and your social network eventually caters ONLY to the questionable stuff. The counterweight to that would be lots of users who put inherent value in the notion that the social network they are a part of 'does not believe in censorship', but I think we all know a vanishingly small amount of non-incel/dailystormer/etc users care enough about it to hang out on the incel/dailystormer/etc social network, where every stranger you meet, is likely tweaked in the head.
Give it some time and I bet soon the same thing again will happen to CDNs: If most CDNs band together to censorship such content, on one hand there'll always be a CDN that sees a mission (and perhaps, a business case) in being anti-censorship. But, soon, the ONLY thing that CDN will be hosting is questionable content. And at that point, I bet plenty of sites, filters, firewalls, internet providers, etc, will just blanket-ban the entire CDN and be rid of it all.
And then sites like 8chan possibly truly cannot survive.
Or not. Maybe they'll find a way.
But if that happens, the 'council of CDNs' will have quite a bit of power to wield. So far the messaging coming from at least cloudflare is that they understand this and take this seriously (and so far do not appear to want to open the can of worms if they can avoid it), but it feels inevitable.