I used to work in veterinary medicine, and there are plenty of vaccine conspiracies in the pet owning community. They cause everything from seizures, to allergies, to autoimmune diseases, and more, according to some of these people. Breeders are a huge contributor to this, which leads to plenty of arguments with vets and pets running around unvaccinated.
It's expensive to get litters of puppies vaccinated, and whackadoodle (I used "doodle" for a reason) theories are a great cover for why you are sending home a puppy with zero medical history outside of hand written worming dates. Unfortunately, it's harder to educate people when it's way cheaper to believe bullshit.
I can only speak to my own experience. Most of their communities I've seen are not a place where nuanced views are appreciated. I saw a particularly 4Chanesque take where a guy was trashing a girl he dated for her interest in astrology. He was more than fine supporting it and humoring it while they were together. Once dumped, though, he had to use it as an example of everything he had to be tortured with in the relationship.
I had a couple of things to say about that kind of attitude, but the whole of my response centered around learning to pick partners who are aligned with our own values and goals. They banned me because of my username. I have no idea why, other than making assumptions about my views and values in a negative way. A peep into my post history should suggest otherwise, but anyway.
I don't have a lot of respect for people with strong views that are sensitive about having them challenged. It isn't a good faith argument.