Well, they decided which sites were OK, and then people SEO'd a bunch of crap into Google's idea of a good website.
I'm no fan of Google but it's not so simple to figure out what's relevant, good content on the scale of the internet, while confronted by an army of adversarial actors who can make money by working out what you value in a site.
We should remember that's partly Google's fault as well. They decided SEO sites were OK.