I don't disagree with anything you say, and yet I have to admit--the obsessive checking, the dopamine rewards: I get those from DW, too. I get a little happy buzz every time I get a comment, and I check my e-mail regularly to see if more have come in. Someone else in my feed recently posted a lengthy manual to how to write posts that will gather more comments, and it's advice people are eager for. The dopamine hits from DW come in with less frequency than they do on FB (well, usually; I'm pretty sure this week I've gotten far more DW comments than FB likes), but that's because, as you say, the platform is smaller; there's nothing intrinsic to DW that prevents it from being a source of addictive feedback loops.