I absolutely get what you mean, though in the case I know best it's in person rather than online; my step-father seems to seek out information he finds objectionable for fun. It isn't especially fun for the rest of us, when each time we go for family dinner he'll find a way to shoehorn in a comment about gay people, immigrants, benefits scroungers, everyone being autistic these days, transgender people, over-diagnosis of mental illness, and my personal vote for most ridiculous, why he thinks coeliac disease isn't a real thing.
Worth noting here is that neither me nor my brother are straight and most of the extended family are neurodivergent. Including both of his own children, so it's not just our side of the family getting friendly fire. He even has a close friend with coeliac disease, who he of course believes is an exception with a real condition.
None of us give in and provide the argument he's hoping to start, of course, which in turn seems to get him even more het up. I'm not sure what he's trying to achieve with any of it, really, but it's draining to be around. He wasn't always like this, either; it's got gradually worse over the last five or six years, and only at home. His friends don't seem to see any of it, always describing him as cheerful, friendly, and helpful, whereas anytime I see him he's annoyed about something he's been reading online.
Though it comes out in person, he does gets most of his news and information from Facebook, so I imagine it's very closely linked to those on the social media who seek out offence for entertainment.