Been thinking about the venn diagram of zako. There's a bunch of different overlapping fetishes, aren't there?

You've got the basic bitch "girls frontline" army girls, usually without much actual guro (or real fighting at all).
Then you've got the clone army girls, usually getting the shit beat out of them by a shirtless hero guy. Then there's also the milfy housewife turned henchwoman thing. And a lot of those different groups either don't overlap or actively dislike each other.

It's a very particular and fragmented sort of fetish, which I guess stops it from building much mass appeal despite how many guys are into various parts of it.