> And I would find invented discussions less engaging
I would predict that I would, too - but, evidence suggests that it was engaging enough to get people interested, so maybe our predictions are incorrect.
In the case of something like Reddit, you come to read content, and once you've readit, you write it, and then read some more. I'm not sure you're ever really sold that you're even engaging with actual people.
These days, I frequently wonder what percentage of comments on any of these sites is genuine (although I happen to believe it's still a pretty high percentage). Its good to assume noble intent, but to also carry around skepticism.
It's much more broad than that. A common sales tactic is to pretend there are other folks interested in what's being sold; maybe this is to make it seem popular, maybe this is to push Buy It Now for a limited (maybe one) item. Some folks will have a fake interested party show up in person.
I would call all of that a scam, even if I'm paying the listed price and get what was promised.
Dishonesty is not sufficient to render something a scam - the scam-ee needs to "lose out" in some way. In this situation, I don't believe they did.