I think its more that people don't want to debate or have discussions that challenges their viewpoints and ideologies and that if you debate or challenge then that is toxic and negative. People like discussions. Just so long as they aren't challenging their ideologies or viewpoints and the discussion is on the path of mutual agreement.
Is it the chicken, or is it the egg?
I won't argue that some Facebook groups and other Forums are becoming rather gunshy about disagreement, but the forums I've called home for almost my entire adult life have remained quite tolerant of opposing views. However, the manner in which people communicate those views often struggle to stay within community guidelines.
Said forums allow for political debates constantly, and while the overall political lean would certainly be to the left, there are a number of right leaning/conservative members. Those who stay around are the ones that find themselves able to communicate their viewpoints eloquently and consistently. Nobody expects 100% agreement on every topic all the time. The snag becomes that most of us have been at this for a decade or two at this point, many of the arguments have been had, re-had, hashed out, and then trotted out again every year or two for good measure. We've been there, and done that, so unless someone is bringing something new to the table, it can get a little exasperating to be literally going over the same points from a year or two ago, even if it's 'new' to someone else in the discussion.
The other side of it is the general acceptance of weaponized communications. We've seen allegations (with what I find to be compelling evidence) of state actor's using troll farms to manipulate political discussions, company's using 'brand ambassador's' and 'influencers' (ugh), and the ever present trolls/donkey caves who are quite eager to continue a crusade against an individual or company for slights as often perceived as they might be real.
I think what I'm trying to get at is that the conversation isn't just about how moderators handle these individuals and topics, but also how the conversation happens, and the individuals that make it up as well. Sometimes having a blanket rule to fall back on can be abused, but sometimes you've just had enough of some fethwits bullgak and it's easier to say that they have failed to uphold the standards set by the community, and then show them the door.
I actually agree that closed echo chambers are often a bad thing, however I have also seen many 'new challengers' wade in to decry said echo chamber... and fail to do anything but fling mud and declare everyone who doesn't immediately appreciate their genius to be sheeple. The ideas and arguments presented should stand on their own, but it's far too common that someone clearly comes in with a chip on their shoulder, or to just troll and stir up muck until they're told off. Some stick around, manage to express their thoughts and concerns eloquently, change minds and perhaps even have their mind changed. I wonder if this doesn't tie to how many of us who have spent a decade or two or more on the internet are just aging? The mind is more open to change and new concepts/ideas in younger years, but that doesn't come as easily later on. I think I was more flexible in some ways in my 20's, less so in my late 30's, and perhaps that comes across digitally as well.
I strive to remain an open minded sort, but when the same gak disturbers start banging on about the same gak they've been outraged over for weeks or months or longer, it's hard to take them seriously or feel particularly put off when they're given a time out. And that's regarding more serious topics like political issues. With a hobby/game, I find it even easier to accept 'the moderator's/admin's house, their rules', because almost nobody is Jean Valjean on the barricades standing against dastardly evil doers, and even if they have a point, many will run it into the ground, losing what little support they might have had.
One of the biggest disparities I see on this is threading of comments. I hate Facebook groups, everything as a nested jumble, which often wanders off topic by the second comment. While a forum, I find Reddit's non-linear approach similarly annoying. Give me forums like Dakka where a topic follows a more measured and chronological pace, with major tangents generally shut down by the moderators over that mess any day.
So, to loop back around, I don't entirely agree that it's a matter of people needing to be in their own little bubbles. That alone is a heavily weighted statement often coming up in political discussions between the US left and right wings, with the latter often condemning the former as 'snowflakes', but in my experience those same groups are no less demanding of their own 'safe spaces' and lack of disagreeing viewpoints (so, same alleged outcome, but with a healthy dose of hypocrisy added on top).