Baseline vs. Privilege

>>I guess there have been thousands of tiny insular countries,<<

Tiny insular communities, at least. Countries? Not sure. Much has been lost to the tides of time -- we'll never know how many highly functional cultures were wiped out by a bigger band of violent invaders.

>> and some of them may have been welcoming of strangers, had no gender-based roles, no religious bias, and been equally tolerant of all forms of relationships, including homosexual, heterosexual, polyamorous, and monogamous. And so forth. <<

No culture is perfect. A healthy culture manages to meet the needs of most members most of the time, while not violating anyone to the extent that it causes constant problems. There will always be challenges. But different cultures cope with them in different ways -- plenty of tribal cultures accommodate uncommon sex/gender identities by allowing them to switch roles or by placing them in a role (such as shaman or sacred clown) which has a nonstandard set of rules. That can work. The vast majority of cultures have gender roles -- but that doesn't necessarily mean either is oppressing the other, because sometimes they're equal. And some things, like strangers and religious bias, are largely modern problems. When people didn't travel much, it didn't matter as much that some cultures were xenophobic and not everybody had the same religion. The contact rate was so low that it wasn't a constant problem. Now that people are moving around a lot more, those challenges are much more of an issue.

>>It seems unlikely that there have been very many, though. To a degree, tolerance is also a quality of large societies, which by simple statistics are going to have more diversity that needs to be tolerated, than small tribes.<<

Tolerance of big differences is something that gets more opportunity for practice in a larger group, yes. But some differences will always crop up, like birth defects and skill variance and sexuality. How a society deals with those is a clue toward how they might deal with other things. Some groups are just more laid-back than others; some are really touchy. A tribe or a village has to be able to maintain strong bonds. A difference that puts other people at risk or rocks the boat too much is a threat -- but conversely, the idea that your neighbors might suddenly decide to kill you is also a threat.

A healthy society has a kind of natural buffer that pulls it toward a state of calm; it's hard to panic them into making a really bad mistake, because the society's virtues and processes have firebreaks built in. If calm is admired, people are less likely to snap under stress -- that's valuable not only in keeping a small group stable, but in making sure your hunters don't panic in the woods and get eaten by bears. If the decision-making process includes a meeting where everyone, or at least a substantial number of people, get a chance to air their views then that lowers the chance of a really bad idea getting through because someone will probably point out its flaws. Conversely, a society that admires brashness will produce people geared to hit-and-run tactics. That can work, but it makes for edgier living. A society with an authoritarian structure can mobilize and control people better ... but that also enables them to make larger-scale mistakes faster. Or gains, for that matter. Big spikes and dips.

Looking at modern examples, America is more buffered than, say, central Europe. We have problems with racial and religious conflicts, but they don't cause the whole country to explode into wars every decade or few. The main challenge is that different countries have assembled solutions to different problems -- in some places, race or religion or poverty or sexuality or whatnot just don't explode. But nobody has all the discovered solutions in one place, and people are darned stubborn about not wanting to try other people's solutions. It's frustrating. If people would swap ideas, we'd work through this a lot faster.