> I remember using a computer with RAM measured in two-digit amounts of MiB
Yes, so do I. It was limited to 800x600x16 color mode or 320x200x256. A significant amount of memory gets consumed by graphical assets, especially in web browsers which tend to keep uncompressed copies of images around so they can blit them into position.
But a lot is wasted, often by routing things through single bottlenecks in the whole system. Antivirus programs. Global locks. Syncing to the filesystem at the wrong granularity. And so on.
FWIW a two digit amount of MB is usually at least 16MB (though with low hundreds of MHz it was probably at least 32MB if not 64MB) and most such systems could easily do 1024x768 at 16bit, 24bit or 32bit color. At least my mid-90s PC could :-P (24bit color specifically, i had some slow Cirrus Logic adapter that stored the framebuffer in triplets of R,G,B, probably to save RAM but at the cost of performance).