It's because having the truth laid out shows that, in fact, the professionals are all idiots too. We were told so much to trust the professionals, and once the internet laid it all bare we see doctors and engineers and police and fbi agents all acting like a bunch of complete fucking morons. It turns out a ton of shit actually was easy, and those guys were just fucking up or not giving a shit.
Of course, that's not true in all cases. Sometimes a moron has specialized knowledge and thus, they're the best moron for the job.
The Information Age we live in has brought ubiquitous access to monumental amounts of information, including difficult and obscure subjects, therefore the perceived standard of being informed went sharply up. The legions of toxic personalities are motivated to show off their (in most cases fake) 'intellect', and due to the massive amounts of tabloid-level rubbish, they have an excuse of thinking they know a lot. They create an environment where knowing X amount of Y becomes a phallus-measuring contest, yet another thing of the psychopathic popularity contest 'society' has become. Normal people instinctively repeat this behavior until they know better, which is becoming more and more difficult. This naturally drains joy out of intellectual discussions.