The subtle genius in this isn't specifically mentioned in the article itself. The genius (ok, that's a bit grandiose) is that it actually helps solve a problem

The subtle genius in this isn't specifically mentioned in the article itself. The genius (ok, that's a bit grandiose) is that it actually helps solve a problem for G+, which is user engagement. In social posts, conversation begets conversation, or, the more user activity there is in a post, the more it generates. By making the posts with the most activity larger (or otherwise highlighting them), the user's attention is focused on the turf that is most likely to pull them into engagement. The less trafficked posts might suffer, but that's of no consequence when the goal is increasing user momentum and engagement overall. My take on it anyway. I think it's a clever idea that aids in solving a familiar problem that fledgling social networks have to tackle. Besides HN and Reddit, I use Hubski, where I am watching the same engagement issues being addressed (albeit in completely different ways). Small things like this are actually a big deal when you're starting out imho.