I know some swingers who have been doing it for quite a while who seem content to keep things as they are. Does that mean they treat their sex partners as disposable? I don't think so, particularly not when the people they are engaged with want the same sort of thing from them. I've certainly had intimate and caring sexual connections that were one and done. Trying to put these non-traditional relationships into too many boxes is never going to work well, I don't think. There's too much room for individuality.
I'm glad that you brought this up. Live and let live.