Lighthouse is already built into Chrome amongst many other tools. Lighthouse scores are already a factor for search result rankings. The fact of the matter is, those junk sites don't care.

Even if these scores were exposed to the user by default instead of hidden away in a dev tool, it's just not a strong enough incentive for those sites to change or users to care. Rankings are more strongly affected by adwords, time-to-first-byte, link juice, etc.