[luckylion]

Freshbot was a well-known effect back then (arguably still is, at least I see effects that look very similar where some new content section will rank quickly and amazingly well for a week or two and then slowly sink to the level you'd expect from such new content).

But in the end, it's network effects, only that this banner seems to enforce it manually and explicitly. The old way would've been to not show apps with few users in the top spots.