I've lived without (much) civilization briefly, yes. I understand pretty well what would be involved to do so for a long time. It's not a sham. Civilization is the real deal.

So, anyway, stealing is almost universally regarded as wrong. Great! No stealing. If a religious minority comes along who doesn't believe in property rights, too bad: we still stay stealing is wrong in this culture.

Now, suppose people lie to you about taking things from Target not being stealing. Suppose Walmart is very effective at secretly spreading this story, and now taking things from Target is not almost universally regarded as wrong.

So it's cool now, right?

No! That people have been misled--and we can tell this really unambiguously by, like, asking Target's representatives--about a specific case does not, in general, override the adherence to the widely-accepted principle.

Murdering people is wrong. If I manage to trick a bunch of people into thinking that, say, Polynesians are sub-human and aren't really people, it's not okay to murder them. If we can't change the Polynesian-haters' minds, we can lock them up when they try to kill Polynesians, right?

That's really all I'm saying, except with shame instead of jail. When something is really clear and follows a nearly-universally accepted principle but some people are clearly deluded, you may need to take non-rational measures to limit the damage they do.

Who is responsible for the shaming? Seems like leaving it to individual initiative does the trick. If standad etiquette is to be polite, but some people are just infuriatingly wrong and advocating for something harmful, you naturally get shaming responses (hopefully in addition to a constant stream of evidence about the wrongness--that should never go away; the shaming is just in addition). Only when the number of shamers people is quite large is this effective (otherwise the shamed just bond into a counter-tribe of similar strength). So the problem mostly takes care of itself, if we let it.

Once a delusion reaches a substantial fraction of the population (e.g. "in case of nuclear war, we will go to heaven and our enemies will go to hell, so nuclear war is fine", "there was massive fraud in the 2020 Presidential election", etc.), then we have a problem. You have to calmly persuade people of the wrongness of their positions, or you don't have a democracy. The challenge of democratic governance is to prevent a deluded or deludable population.