I gave you are very direct example for a totalitarian echo chamber becoming murderous. The Soviet and Chinese famines. The officially dictated story became beyond critic and millions died as a result. https://en.wikipedia.org/wiki/Lysenkoism
I also mentioned Dallaires pleas to the UN for access to radio equipment to be allowed to air a counter narrative to the genocidal government aligned ones. Something he addressed special weight to in his "Shaking hands with the devil". Which should say a lot about its importance.
>If I understand you correctly, you appear to be making the argument that if we kick certain groups off the public communications fora, they will meet in secret and become an unseen force that overthrows society.
No, quite the opposite. Trying to ban people you dont like from communicating will result in a totalitarian echo chamber. Thats a slope and you willfully ignore the need for breaks. That quickly turns murderous. Because determining what should and shouldnt be censored and its second and third order effects is an infinitely complex problem that you cant address with intention alone. And will quickly be exploited for monetary/ personal / political / tribal profit. Trying to control discourse is a slope and by making self hosting impossible you are destroying the possibility to erect warning lights. You are willfully heading for a cliff.
Your error stems from being focused on the who of the story and at the same time ignoring practical limits. I am telling you if you are at the point in which communication is restricted enough, there will soon bee armed men and horror if your only safeguards are good intentions. There is a causal relationship, power becomes uncontrollable and slip from your hands as the official story and reality collide more and more and you become incapacitated by it. You trying to solve this with feeling competent enough and more armed men / state control is how that always works. Those are usually the same people who drag you off into camps. After all, you ignored safe use in favor of feeling good about the story and somebody like Stalin or Hitler doesnt mind taking over. The German justice system is a great example, many judges just continued to do their job with their career spanning Weimar, the third Reich and West/East Germany.
Even if you are delusional enough to think that your totalitarian echochamber will be the first one able to overrule reality, people will reliably react and that reaction being unguided as well can easily turn fascist. It was already visible with the various stay behind organizations throughout Europe that were intended as a safeguard against a totalitarian power grab. Or with the KPD as a major topic for NSDAP election run up. Caricatures and bogeymen pose the threat of becoming the lesser evil if the situation deteriorates enough. This isnt a matter of tribalism but one of guaranteed conflict and atrocities. There is no acceptable or safe version of totalitarianism, its by its very nature corrupt, self destructive and brings out the worst in people. Even if "your side" ends up on top, it will be a distorted, corrupt and dysfunctional monster. Or do you think there are many fans of Göring even among Nazis? Large parts of the admiralty of the soviet pacific fleet dying in an overloaded smuggler plane is another good example: https://en.wikipedia.org/wiki/1981_Pushkin_Tu-104_crash