That's true, but the trophies and points are barely any value in the day-to-day. For example, in deciding to reply to a snap, the thought "My score's gonna increase if I do this" barely crosses the mind.
It's always just about keeping the conversation. And since a lot of the conversation is filler that need not be saved forever, snaps have a unique position.
The bit of game theory they actively present is Seinfeld's "Don't Break the Chain" technique. Snapchat marks and elevates contacts you individually snap at at least once a day, moving those contacts into more-and-more personally named categories ("close friend", "best friends", etc).
That bit is right in your face and rewards you for increased use.
I had no idea that was the case, but that's some next level psychological shit to be pulling on a predominantly teenage customer base. Does no one see the proposal to do something like this and think to step back for a second and consider the effect its going to have on people's lives?
It's always just about keeping the conversation. And since a lot of the conversation is filler that need not be saved forever, snaps have a unique position.