Well, granted my sample size is extremely small, but I've only ever known 2 polyamorous groups of people well enough to visit their home. And in both cases, there was always 1 person who wasn't as happy as the other two and was tolerating the scenario due to pressure from the person they considered their 'significant other'.

The dynamic was: A & B would be considered spouses to each other, A wants to bring in additional person C and create a trio under the banner of "polyamory" and B consents (because they are willing to accommodate anything A wants to make A happy). So person C enters the relationship and they form a polyamorous-trio, but instead of it being a true trio, it's more like A & B still have their relationship (now burdened) and A & C have a relationship, but B & C don't engage much. This is the exact scenario I have witnessed in the only 2 households I've ever known doing it.

That's given me the impression that arrangements like that usually serve the needs of one or two people but often leave at least one party secretly unhappy. Maybe if more people actually witnessed polyamory working as it's been proclaimed, there would be higher opinions of arrangements like that. But I sure haven't seen it - my current conclusion is that it's just not within the bounds of human nature for this kind of relationship to work.

Here I am surprised that a person is surprised that non-preferred sexual acts would trigger visceral disgust.

I mean, sex is actively disgusting unless your partner just happens to have the right combination of signals to transform it into something non-disgusting.

The wonder is that any sex ever is seen as non-disgusting.