It goes both ways - people flag legitimate claims of conspiracy and dunk on them, too. For example in the 40s, the idea that cigarette manufacturers were conspiring with the medical industry. Or as a 2010s example, that the NSA is secretly recording everything we are doing and saying online (PRISM).
My biggest take-away is that you need to be paying attention, you need to get your news from multiple sources, and it helps to have strong foundational knowledge that you can use to gauge the reliability of those sources. Usually the establishment is right, but sometimes that random guy on the internet is right, so it's important not to discredit anyone solely based on their pedigree. A process that, obviously, the kool-aid drinkers in that subreddit didn't seem to have a grasp on.