Your experience with Pocket Change?

Does anybody have any experience with PocketChange? https://pocketchange.com/

If I understood it correctly, you can reward your user for certain actions by awarding them this virtual currency, which they can then use to shop at certain vendors. This is supposedly free for the developer, and they make their money by charging those vendors who get some brand exposure through this. Developers don’t make money directly from it, but can use it as an incentive to get more user activity. Sounds really interesting in theory, I wonder how it works in practice? What keeps app developers from just freely handing out that currency if it doesn’t cost them anything?

Some apps use this on Google Play.

However, I have a feeling this goes against the new Google Content Guidelines which prohibit offering stuff to users which can be encashed elsewhere for real goods.

Maybe someone else can confirm this better for you.