> Yeah, like your example, Facebook. Ever since their redesign, I've switched to only using the mobile+noscript site (on desktop), because the SPA version is resource-hungry to the point that it regularly DoSes whatever browser thread it gets assigned to and has UX that, ironically, seems to be terrible as anything other than a mobile app (they've replaced text with abstract square "touchable" buttons and introduced airy spacing everywhere that allows you to see maybe about half a post per screen).

I have literally not heard of anyone complaining about this (not that your argument is invalid). A whole lot of people are just not gonna bother or check how resource intensive it is.