No, read it again. The point is no one pays programmers or artists, and no one sells the game. It's called "open" source because it's completely open. Whoever wants to add to it can add to it. Whoever wants to play it can play it. Perverts can do whatever they want on their own system, but the core files would be strictly reviewed before being posted.

It's called fun. It's called learning about game design and development.