I don't know why, but I would say for sure lots of women seem to be quite unaware of this kind of thing even in the past. Maybe they just assume people cross-dressing in the past were really trans?
I have heard people say in the past, when talking about the cohort of gay men who like things like cottaging and have very high numbers of sex partners, that this was caused by lack of general acceptance of male homosexuality, and that when we had things like SSM, it would go away over time. Perhaps these omen believe that men who cross-dressed in the past did weird things because their trans identities were not accepted?
As far as the motivation in itself, I think the closest thing a lot of women can somewhat understand relates to people who at some level are aroused by the idea of being watched while having sex. I'm not sure if this counts as a paraphilia, as it seems much more common including in woman. But part of the psychology of it involves the individual putting herself in the head of the person watching, so being both subject and object.
I suspect men who develop things like AGP similarly are imagining themselves as object, as if through the eyes of another, but somehow they want to see themselves as the type of object they sexually desire.
Anyway - that's my best guess. I have thought that perhaps the general capacity has something to do with the fact that we naturally live in tribes, but who knows.