Back in the seventies, most of the speakers that I saw in the stereo stores were the box type that sat on the floor without any feet.Maxell ad? Anyway, I remember the dealers doing that. Maybe they didn't have room for all of them with stands. Stands didn't seem as common either.
Another possibility, a lot of young people were buying audio then, and maybe they didn't want to break the bank making them think they needed stands also, and may pass on their store. A lot of those speakers did need elevated on stands IMO. I raised mine.
I can't see why the subs would need to be line of site to your ears, if they are really only for the bottoms octaves. If it was at higher directional frequencies, I could see them being at ear level. Just my thoughts FWIW.