If you're using Steam Big Picture, you can leave multiple accounts logged in to every device and buy games on them; I did this when I ran fighting game tournaments during COVID--accounts named [channel]1, [channel]2, and so on. (Why you can't do this with the desktop UI is certainly a wart, though.)
Given this, rearchitecting their infrastructure (which pretty universally considers a single account a single active user) for a fairly niche case is probably low on the list.