i dunno maybe locking the female for a while so he can finish his orgasm so all of his cum would make sure she's impregnated in her season of heat i think if the knot didn't exist some of cum wouldn't be able to get in her womb so she is less likely to be impregnated or not at all due to little cum in her womb though a female could trick a male she's in her heat so she could get a good fuck
