Google was forced into that by improved "search engine optimization". SEO used to be about things like keyword stuffing, but as Google made their search engine smarter, SEO companies made their search spamming smarter. There are now SEO operations using machine learning to reverse engineer Google's algorithms and then automatically spam just enough to stay under the threshold.
In 2010, Google tried using "local" data to improve search. That turned out to be extremely easy to spam. A classic example of this can be found by searching for "laptop repair bradford pa". This brings up "Illusory Laptop Repair", located in the middle of a railroad crossing. A SEO expert created that phony business listing to demonstrate how bad Google was at detecting such spam. Google still thinks it's real.
In 2012, Google tried using "social" data to improve search. That worked even worse. Fake Google accounts created to create fake "+1"s may have exceeded the number of real ones. Google "+1" are still for sale; the going rate is about $0.10 each.
Meanwhile, links aren't as useful as they used to be. Who creates a link to a retail outlet other than on social media any more? Google is trying all sorts of "signals", but in heavily spammed areas, they're not doing all that well.
Yandex has been trying search that doesn't weight links at all for some heavily spammed categories in the Moscow area. It seems to be working for fake real estate ads.
(We have a partial solution - find the real-world business behind the web site and check it out in hard data sources, such as Dun and Bradstreet or Experian, which have business credit data. See "sitetruth.com/doc".)