Never had much success on LAF, my 6mm went down like a lead balloon and not much in the way of interest of my 15mm either. LAF always seemed to be for 25mm branded high quality finished games to me. (which my stuff is not) Besides, I have a vested interest in making TWW the place to be! 😉
I would not be that negative. There is a small but active group of people posting 15s.
Nevertheless, when compared to the vast majority of posts, your general estimation is probably right: LAF is way more interested in 28s and the posts of masterful painters in that scale draw most users.