Very good and relevant points.
On the other hand, under uniquely challenging and difficult situations people can work together to a degree that wasn't really possible before times got truly rough. The French underground resistance in WWII had people working together to the degree necessary to be a cohesive and significant force, but then few things motivate people quite like the imminent and likely destruction of their nation, culture, and way of life (and the constant threat of summary execution).
I've visited a few intentional communities aka "hippie communes," and they began with the goal of coming up with new ways of living. But the ones that endured for more than a decade (which were the ones I visited) had all pretty much reinvented business as usual and largely resembled miniature versions of regular society except with a lot more passive-aggressive bickering at council meetings vs. the aggressive-aggressive bickering among mainstream city councils or County Commissions. One such community (at least) experienced repeated cholera outbreaks in the 1970's because of either a general ignorance of basic hygiene or a belief that it was oppressive or something. So naive idealism is clearly not the right motivation to come together around since shit happens, literally, and needs to be dealt with properly.
They didn't come together to help each other endure a global catastrophe, so observations of such communities' social and political dynamics are probably not very relevant to a SHTF context and frankly I couldn't put up with living in the ones I've been to. No way in hell, actually.
The main challenge with all this is that people will probably be able to live a lot more cooperatively once cooperation becomes a matter of life-or-death, but bringing people together before that happens risks driving them all apart with the usual acrimonious bickering and petty power politics that occur in most groups of people no matter what the context. On the other hand (or is it the third hand?), not bringing people together before shit hits the fan pretty much precludes any chance of doing so once the shit's flying everywhere. And being alone is fatal if put under siege (surrounded).
So what I'm envisioning (and it's a work in progress) is more like a home base and training location for a like-minded group of survivalists who take the low-tech, primitive skills approach rather than the stockpiled ammo, fortified bunker approach. So most involved wouldn't live there most of the time, though all would be encouraged to purchase adjoining properties to expand it and efforts would be made to get the local neighbors on board. Those involved would show up for practicing survival skills and learning new ones and then go back to their regularly-scheduled lives (assuming the pandemic ends and we'll be able to do that at some point). If shit hits the fan for real then we'd at least have a place to meet and face whatever comes as a (skilled!) group instead of alone (though both have pros and cons).
I have a friend who lives in the deep South who has the most common last name in the County where she lives, and to get to her house you have to drive past (and through) the properties of dozens of her blood relatives who've all been living in the area for generations. She's a sitting Probate Judge, and some of her other kin are also elected officials, police officers or Sheriff deputies, and so on. They run the place, in other words. If you have the right name when you get arrested in that County it goes fairly well. If not, it doesn't. Is that fair or just? Fuck no, but then fairness and justice don't really have anything to do with what actually happens.
Fully half of that County is basically a huge but very low-profile compound (i.e., no fences between all their adjoining properties, no formal organization or hierarchy but none ever sell their land to non-family). It's composed of one very large extended family and if they wanted they could stop all travel through the County in a matter of minutes. To an outsider it looks like anyplace else where everyone lives on their own mostly-rural properties in their own houses (which is the case), so they are not living in anything resembling a commune or intentional community though their interests are closely aligned because they all see the great benefit to being part of a family that is capable of running the place whether society is functioning or not.
I know of several other identical arrangements in North Georgia and Mississippi (I have a weird knack for getting people to tell me things they don't normally talk about), and I was even given a name to drop and a password to use to not get shot on sight if I rolled up to one after a SHTF scenario and the guard didn't recognize me (they prep and plan and practice for various SHTF scenarios but are not the kind of meatheaded reactionary and racist "militia" type groups and in fact one was created to counter the potential threat from such groups). And I was assured that if I went to the area I would definitely be confronted by armed guards popping out of nowhere, so I'd better not forget that password!
We might have to suck it up and learn how to compromise with and tolerate each other better than we generally do lest we some day face the unimaginable all by ourselves.
I might not be able to figure out any viable answers but I'm not going to go down without trying, and if it's all doomed either way then I'd still much rather experience a failure in execution rather than one of imagination.