I think the joke is generally that it is the basic necessity and one would generally expect people to create a more homely environment (eg furniture for guests

I think the joke is generally that it is the basic necessity and one would generally expect people to create a more homely environment (eg furniture for guests or eating, storage for clothes, maybe bookshelves with books or photographs or whatever). The joke is not ‘floor mattress bad’ it’s ‘no furniture nor decoration despite ample means = weird’. The thing you saw was just a derivative of the original meme which was a single mattress on the floor next to a phone charger. I don’t really think the thing you saw was really trying to get people to be more consumerist.