Id very much agree on both the primal thing as well as pee being less of it than the pose.
Let he who has not been at a party ,saw girls heading to the treeline and thought "hehe butts out" cast the first stone. Don't worry I'll wait.
Frog-pose is a very feminine and vulnerable pose, plus the ass is phat about 125% of the time in said pose. Whether Ole girl is pulling a wagon prior or not. And yes, the desperation vids can trigger "oh-ho. Bitch in distress, Ill save you" response I think it doesn't quite hit the nail on the head.
As you said, we all stumbled into it. But gen