i believe the obstacle here is to have as many players as they can on the site. because without challengers, it would not be exciting to create your own challenge. i guess, this is one of the bottlenecks in a pvp betting site. if you can't attract players, the challenges would be dull and not interesting. maybe, the site has idea on how to attract these bettors and create their own challenges to make it a very interesting one.
There is an extra bonus for the creator if he wins and another strategy to market your casino, the same on the forum that has a signature campaign that brings awareness to the people and the gamblers as well. We know how boring p2p is and not everyone uses this since the chances of getting of bonus is not that wide. However, probably I have a wrong understanding.