IMHO, ancap norms enable multiculturalism. For example, Islamic law has very specific rules about credit and debt. While you can not set up a westernized bank in an Islamic country, you could easily set up an Islamic bank in a free western country. (well not really, there's a bunch of regulatory crap nowdays, but that's not cultural) Same with the dress code. While people of Islam can easily practice wearing a burka in a free western country without legal consequence (well, the gestapo checkpoint at the airport anymore, but that's not ancap culture anyhow), it would be very hard for a western woman to go around wearing a bikini in an Islamic country. In the USA, there were both large Bosnian and Serb communities that did not fight, while they did in Europe where they had the power to control each others freedom. Also, take a look at the Bahamas that ranks relatively high on the economic freedom index, but is overwhelmingly black with a slave heritage. Well, western culture and white people in particular, have no problem at all getting along over there.

Also I think it's important to make a distinction. There is free market multiculturalism, and state imposed multiculturalism - where the state tries to force a culture down your throat. The former is cool, the latter is shit.

Also, I think it's important to make a distinction. There are cultural norms that violate freedom and property rights, and cultural norms that don't. The former is shit, but the later is cool.

Even in the USA. In communities that are overwhelmingly or mostly black there is lots of racial tension with black people, but in communities that are overwhelmingly white, there is little racial tension with black people. If it was cultural norms, one would think that the opposite would be true. Black people living in communities that are overwhelmingly white would be the most miserable, and be feeling the most oppressed by far. But that doesn't happen. That's because having the different races doesn't enable racial tension, even having the different cultures doesn't enable racial tension, but when cultural norms enable socialism, then all hell brakes loose and the whole thing becomes a miserable shit-hole.

You could see that in South Africa to a smaller extent too. Black people were miserable there because there was a lot of racism, but then after Apartheid ended, socialist cultural norms took over and it became a miserable socialist shit-hole where even the black people are far more miserable than they were before under the cultural racism. Ironically many black people there are now reported to long for the days that the white people were in charge. (same with Zimbabwe) It wasn't because they liked the racism, but because the parts of western culture that were anti-socialist made everybody far more happier and far more able to get along.