I've posted on "Who's hiring" for years now, and hired many engineers from those posts. We reject the vast majority of candidates, and to those who we reject, it might seem like we can't hire "a single candidate." That's not true - if it were, I'd stop posting here!
No, that couldn’t be it. Yes, the incentive exists for them to do that, but I’m sure their conscious wouldn’t let them lead people on and waste their time like that.