There are many apps - SkyView for example. As you say, they've been here for several years, so I don't understand it either.

In a very literal sense, sure.

But it isn't very interesting, now is it?

What's the point over a rendered plane? Gameplay would be identical.

What is augmented? Or to phase it another way, what from the real world is integrated into the game?

It is just using the camera and other motion sensors to track movement. It isn't augmented reality in any sense.

It's so "little" it's more like projected virtuality. AR used to let you fight in your room and bounce stuff against your walls etc.