I think that's honestly just a side effect of it being such a popular subverse. It's one of the first a lot of people subscribe to, and also I think a bit of arguing should be expected on a conspiracy subverse.

I'd just like to point out, that even if vaccines extremely rarely caused autism, they would still be much more helpful than harmful. A world without vaccines is a world where vastly more people die of trivial diseases. Essentially, an extremely small risk of autism vs a pretty good chance of getting smallpox. Or measles, or any of the other fucking diseases you can avoid with vaccines.

Although the anti-vaxxer drama being started by the vaccine companies may be possible. It does make them look like the good guys for fucking once. I wouldn't be shocked if they are secretly totally fine with the anti vaxxers, maybe even helped start em up.