Is that what being a promotor is about though? It's about promoting his night or residents and the best way to do this is playing to different crowds.
I run two nights Cypher and Neo for three years but I don't DJ myself. I'm interested mainly in getting my ressies as much good exposure as possible. DJ swaps are one way of doing this.
Don't you think it's a bit arrogant to think that you are better than the other DJ's (ie the promoter that gets the swap bookings) ?
One problem is that everyone can DJ and there's not enough sets to go around.
You have to see things from the point of the promotor who has invested all of his free time and money into putting a night on. A lot more risk and time than spinning records in your bedroom.