I don't agree with your uncertainty here.

If Google imposed a seriously strong penalty against bloated websites, people would promptly stop making new bloated websites, and would invest in lessening the bloat of their existing sites.

I can't think of a more certain spur to action than Google imposing a threat of going undiscovered. It's perfectly normal for web companies to flout the GDPR, say, as it's laughably unenforced, but Google rankings are no joke.

edit: a few tweaks