I think you're overestimating the average internet user. A lot of people think that because they view something online, it gives it authority. They fail to understand anyone can (and does) post content online.
I've often thought this way of thinking is a remnant of the media we've consumed in the past, where there were higher standards because producing media was more exclusive. Think print, radio, TV. On those mediums not just anyone could produce content.
It is so strange to me specifically because the cohort that seems to be eating this up(my parents age, I mean) were the same ones telling me NOT to believe anything I read on the internet when I was young and the internet was new.
It's easy to disbelieve what you read on the internet when it's one voice in a thousand. But increasingly, all thousand voices are telling you what you want to hear.
I've often thought this way of thinking is a remnant of the media we've consumed in the past, where there were higher standards because producing media was more exclusive. Think print, radio, TV. On those mediums not just anyone could produce content.