Couchsitters have more job opportunities minding the couches while their owners are away. Divansitters are more niche. Most people have couches nowadays

I’ve never heard of a divan-potato so I’d guess the divanlayer is a fair bit less likely to be a tuber.

Couchsitters when couchshitters come in

Divan layers just have a certain elegance that couch sitters will never achieve.

Keeping your feet on the ground makes you MUCH less likely to fall asleep while sitting. I suspect the couch sitters are more alert.