As a game guy, I think it would be better to call them "user engagement techniques" or something instead of "gameplay elements" when gameplay is not at the core of the experience. To be fair, I guess it's like how game designers talk about "toy factor" when something is fun to play with pointlessly.

That said, I love the trend, from Yelp to all these YC companies, of deliberately planning the user experience to include these systems.

I don't thing games deserve as much credit as they sometimes get, either. I went to a Cub Scout troop where we had the same kind of points, rank and achievements that are typically denoted as "gameplay elements" today.