This is a good point, although maybe I’m just unlucky, but quite a few times over the years, I’ve encountered friends, and friends of friends, who were vegetarian or vegan and seemed to make a primary hobby out of shoe-horning that information into any and every conversation they could. And every time, it was very deliberately and openly presented in a way to praise themselves and demonize anyone not like them.

Not only is food very foundational, as you’ve said, but I also strongly feel that a reason this particular set of -isms is such a lightning rod is because (perhaps due in large part to that foundational aspect of food in society), it seems like vegetarianism and veganism very much becomes who someone is, as opposed to simply describing an aspect of their lifestyle.

Not only that, but it becomes a part of their Identity in a way that frequently impacts the people around them.

So someone is a Catholic. That’s cool. I’m not one and I might have my issues with the Catholic church, but unless they’re extremely devout, chances are, their Catholicism is more “how they worship” and less “who they are” in everyday interaction. It just isn’t likely to affect me, and as such I’m much less likely to really care. As such, I’m cool with Catholics. Add to that: most Catholic people aren’t painting their religious belief in superiority either overtly or implicitly these days. They’re just going to mass on Sunday and doing their thing.

On the other hand, someone is vegan. That’s also cool. I might have preferences and a lifestyle that conflicts with their views and vice versa but we can coexist, and our preferences on what to eat won’t ever lead to conflict between us, right? Well…if they’re a coworker…or a member of a friend group, now any and every time that group of people wants to eat, that foundational aspect of society, now the group must accommodate that -ism which they don’t share. And that’s probably fine for everyone in the group sometimes…and some of the group all the time…but generally speaking, looking at all of the group, all of the time, that’s statistically likely to eventually rankle at least a few people. Then, depending on the individual, there’s a very real chance that they eat with this group, some of which may already be annoyed by having their food options limited by the choices of this individual…and on top of it, that individual takes that opportunity to make a comment that invokes morality into the situation…and it should come as little surprise that this type of person gets a generalized negative reputation.