Good question. Counter-example: news sites. Very lean in '90s and early 2000s, but now still serves the same thing but with more tracking (so JS), autoplaying video for another newsitem (so additional data is consumed + battery life), and the essential content (what an average user wants) is still the same. Complicated visualization done wih JS+Canvas? Fine with that. News item? If it is a human, it would be obese already.
TLDR: News sites for reading news has certainly got heavier.
TLDR: News sites for reading news has certainly got heavier.