And then spammers or unscrupulous competitors will flag legitimate sites as spam, pushing the signal-to-noise ratio to the point of uselessness. Plus, few users will actually flag correctly. Most will simply not notice, or not bother, others will flag perfectly legitimate results as spam just because Google wasn't psychic enough to know exactly what they want from their vague query.
And Google already has a pretty good metric in the bounce rate without the need to add a "flag" option. That is, if you go back to the search page shortly after clicking a link, that link is probably irrelevant. I guess that SEO spammers found a way around that.
> Google can easily afford to have people verify a link should be taken down before doing it.
Google is super rich, they probably can if they want to dedicate a huge amount of resources to that. It is hard for humans to win against bots in this game.
> If we forced spammers to make web pages attractive and informative to humans instead of crawlers we’d be in a much better place
It is something spammers do. They make the page attractive using psychological tricks (like typical clickbait). They make it informative by copying parts of Wikipedia or StackOverflow. It does not make the world a better place, and it is something Google fights against, with mixed success.
And Google already has a pretty good metric in the bounce rate without the need to add a "flag" option. That is, if you go back to the search page shortly after clicking a link, that link is probably irrelevant. I guess that SEO spammers found a way around that.