As a brutalist web design fan I was a little embarrassed to have dropped large images right in the bodies of blog posts which then aggregate into an unpaginated blog page. The hanging side task of updating my blogging script to make a thumbnail and show that in the article instead of the original image formed a minor ugh field around the blog in general. Well, the answer was much easier once I gave it some attention: Image alt text can be link text instead. Page size is then as tiny as I could wish for.
The greatest single orders-of-magnitude leap in capability I ever witnessed was when I moved from 56kbps at home to 100BaseT in a college dorm room. Web pages of the time were sized to fit in the patience budget of a dial-up user. Overnight, everything loaded like lightning. The web felt faster than my hard disk. And as broadband became common and page sizes grew, it has just never seemed that good since.
There are other good points on this topic: In developing countries, a user’s network speed may make your comparatively bloated site or service inaccessible. I admit that’s not top of mind for me and I’m mostly motivated by my own experience. I just want it to be as good as I remember, and I hope my memory is accurate.
When it’s up to me, let apps be apps and let web pages be printable rectangles again. My browser already lives in a multi-window environment; it doesn’t need to be layers all the way down. A little on-page interactivity can be OK—I’ll praise the hamburgers on the mobile views of swift.org and signed-in GitHub for disclosing their menus by pushing page content down rather than covering it.