It does in my mind. I fully expect visiting any of reddit.com, github.com, notion.so, or meet.google.com to have the chance to pin a cpu core at 100% for as long as the site is open.
At this point, I expect the average webpage to use more CPU than any of the video games I play. The only reason I had to upgrade to my current machine is because a 2021 CPU (intel gen 11) wasn't capable of running notion.so or google meet anymore, it still ran all the video games I care about just fine.
CPU bound games examples: Chess, Go, Final Fantasy XIV, Elite Dangerous, and any competent Civilization / 4X or turn-based strategy game. Yes, you can dial up the graphics on these to force them to be GPU bound, but they’re each CPU bound in their own unique ways. Perhaps none such games appeal to you, but as with above, extrapolating from personal preferences is a non-starter.
Non-tech people teach each other to force-quit apps to stop their battery drain. Websites aren’t apps, so their phone ‘randomly’ gets hot sometimes and they either have no idea why or just try closing all tabs in a vague hope that it works. Sometimes a webpage uses up all their data for the month downloading ads and so they stop using the web over cellular at all.
This is the baseline level of competence that improving the web must be aiming for — not ‘web developers will understand that the tab is using lots of battery and must be closed’. Making the web better is not about making the web significantly more battery-hungry, no matter how pretty it might seem. No visual advancement in radio button UX is worth a continuous repaint in JavaScript.
The websites I mentioned use more cpu and memory than most games in Civilization the series, which are largely competently developed. My previous laptop could play civ 5 at a higher framerate than it could scroll github diffs or notion pages. Civ 5 handled full-speed keyboard input, while notion doesn't let me input text at my roughly 100 wpm typing speed.
I agree that we shouldn't be expecting users to figure out how to close the right tab, however I'm reporting the way things currently are, which is that webpages are poorly optimized messes.