It's the continuing advancement of post-reality into more and more of people's existence. Back twenty years ago when we were all just dipping our toes into the Internet, the majority of our existence was still rooted in traditional society. You might dig around on the Web and find "conspiracy" discussions, but you knew that these topics wouldn't pass the bar for conversation with your family and friends, so you just compartmentalized them. Eventually you either found a way to process the grains of truth in such thoughts (eg the military industrial complex didn't "do" 9/11, but they greatly benefited from it), or you kept on compartmentalizing those thoughts until you forgot about them for whatever reason. Now most of our social interactions are online, and at the very least mediated by online communities. When you run across some outlandish theory, it's easy enough to share it, even if you editorialize a bit to soften the blow- "does anyone think this might be true", "sounds crazy but I'm just passing it on", etc. You don't have to leave the post-reality environment, so it never even occurs to you to temper it down a bit to avoid being the crazy person (coupled with people's lack of physical empathy when communicating through text. I suspect us early Internet citizens are more reflective here, because we learned to overcompensate with left-brained sympathy early on, before pictures supplied a substitute empathy signal). Additionally, most of this communication is done through third party intermediaries whose main metric is to maximize "engagement", and so they'll amplify the signal to those who are receptive, and hide it from those who would shun you because of it.
Furthermore, I characterized our previous existence as "traditional society", but it really wasn't that either. Rather it was a different post-reality as mediated by broadcast media, progressed to be owned by a handful of corporations. This kept us all on the same page and working for common goals, even if the goals weren't necessarily in our own interests (eg widening wealth gap, elective wars). That is what passed for the traditional zeitgeist that we were steeped in, and everyone accepted it because of the massive social proof from The Important People on TV. Now looking back, we can see that the traditional zeitgeist was not in our interest either, and so it does not offer a compelling focus point to return to. And so we're just kind of lost and rudderless, looking for new directions to suspend our disbelief for.