These people absolutely were reading Reddit comments from a year ago to help them parse unfamiliar jargon in some document they found or make sense of what's going on in an image or whatever.
The LLM-only AI just hands you a fully-formed opinion with always-plausible-sounding reasons. There's no cognitive prompt to make you consider if it's wrong. I'm actually deliberately cultivating an instinctive negative distrust of LLM-only AI and would suggest it to other people because even though it may be too critical on a percentage basis, you need it as a cognitive hack to remember that you need to check everything coming out of them... not because they are never right but precisely because they are often right, but nowhere near 100% right! If they were always wrong we wouldn't have this problem, and if they were just reliably 99.9999% right we wouldn't have this problem, but right now they sit in that maximum danger zone of correctness where they're right enough that we cognitively relax after a while, but they're nowhere near right enough for that to be OK on any level.
I've encountered enough instances in subjects I am familiar with where the "I'm 14 and I just googled it for you" solution that's right 51% of the time and dangerously wrong the other 49 is highly upvoted and the "so I've been here before and this is kind of nuanced with a lot of moving pieced, you'll need to understand the following X, the general gist of Y is..." type take that's more correct is highly downvoted that I feel justified in making the "safe" assumption that this is how all subjects work.
On one hand at least Reddit shows you the downvoted comment if you look and you can go independently verify what they have to say.
But on the other hand the LLM is instant and won't screech at you if you ask it to cite sources.