Not as much of an overlap as you might think For one, the leather and kink communities first started with gay dudes while the swinger's parties are generally the straightest thing imaginable since the default is married couples wife swapping.
There's also a ton of reasons someone would want to go to a dungeon without necessarily being cool with having public sex. And on the other hand, someone who likes to fuck multiple people can still be 100% vanilla so they would have no reason to go to a kink event where most people aren't there to bang.
