It wouldn't be cutting off a part of someone's existance if they would be temporarily lessening an annoying feeling that might bother them all day long when they are in-between relationships or not with a lover.
Dunno about you but for some women self-serving does not last as long as the real thing...ahem
Ironically the Pill or other hormonal birth controls are a "cure" for this... but that is extreme!
Maybe people who will sleep with just anyone are actually gifted in some strange way.