I remember when I used to run gnome 2 (i.e. mate) on a machine with 256mb of ram. It was a full experience and it worked with youtube videos and so on. What are we even doing .
Sure, back when videos were at most 480p/720p that's feasible.
I'm not saying software is any more efficiently written these days but I do think it's important to recognize that just the act of pushing more pixels on its own requires more RAM.
Honestly, no. Prior to 2009 there were almost no 720p videos on the platform. In 2009 Windows 7 came out with a minimum requirement of 1GB RAM (Vista in 2007 also already recommended 1GB). What I'm trying to say is, 1GB wasn't much even before 720p got common. The amount of people watching 720p on systems with less than 1GB has likely always been minuscule.
I'm not saying software is any more efficiently written these days but I do think it's important to recognize that just the act of pushing more pixels on its own requires more RAM.