Those people have always existed. When I was a kid in the 80's, supermarkets carried tabloid newspapers with headlines like "Boy born with head of a bat" or "leading telekinetics agree that world will end in six days". The difference now is that while most of us just shook our heads and dismissed those tabloid newspapers, nobody was pressuring the supermarkets themselves to ban their sale.
Editorial standards in the normal media didn’t allow for the type of propaganda that is mainstream today. The NY Times didn’t write about Bigfoot, because it’s silly and would detract from their reputation. Who would take a publication talking about batboy seriously?
Reddit/Twitter/Facebook specifically denies accountability for anything - they hijack the credibility of organizations AND you to drive engagement, period. If the content is gross, it’s not “their fault”.
So when deluded people read something outlandish online, they're now left free to assume that some halfway-trustworthy real-world entity must be endorsing those claims. There's no expectation of critical thinking or skeptical debate about what we see online because real-world norms are very different, and it all gets conflated as "what's mainstream".
Why exactly is this a problem?
The problem is, it's 2021, and the raging dumpster fire of social media platforms has created a world where extremist insanity has become mainstream public discourse. People who believe that reptiles posing as human beings run the earth are have a platform and some sort of earnest following!
People like to scream "censorship" and social media companies rally behind that and their protection from liability. Arguments are made that making editorial decisions about what gets purchased is a moral or legal risk. That's a bunk argument, because social platforms have no problem at all promoting dangerous, wrong or even illegal content to maximize engagement. Let's be real here -- for all of the weighty principles brought up here, a significant chunk of reddit engagement is porn.