(i) "this is the sort if story that, if true, would be widely reported by mainstream media or at least mainstream media of a certain political persuasion" is a pretty good heuristic for discarding stuff that sounds plausible and really big but is only reported on the comment section of AltFreeIndyInfo.net

(ii) if you can't believe mainstream media, it's hard to search for information that might contradict $radicaltheory, never mind trust someone else's thoroughly researched and sourced one. So even if it's a pretty wild theory that lots of other stuff seems to contradict and very little seems to corroborate, how can we be sure it isn't a coverup. Scepticism about well established facts leads to agnosticism about the veracity of well-established fiction.

(iii)"if you tell people this and they laugh at you and say it's ridiculous it's because they're the credulous idiots who believe anything they read in certain sources" is a very powerful meme.

(iv) people who don't believe in certain sources still tend to want to get stuff they can believe in from somewhere, and the average website that concurs that MSM is not to be trusted and embraces the meme that its reader base are the true freethinking sceptics publishes considerably more fake news and terrible takes than the mainstream media

What the last few years has really brought into sharp focus is that many people who distrust "official sources" (mainstream media, scientists, etc) seem to unquestioningly accept fringe sources, so long as it matches their prior beliefs.

Many of these same people consider themselves "skeptics" because they instinctively distrust the official sources.

They are primed to ignore any contrary evidence, that would disprove lies they are being told, that they see on MSM or in fact anywhere. Once they believe a specific channel of information or community is the only one they can trues, they can be sold on anything.