Yep. There are multiple companies that build those blogs en masse. It's called Content Marketing. Those companies are always on the lookout for popular keywords (they use SEMrush, MOZ, etc) so they can build extremely shallow 1000-word blog posts around them for their customers.
They pay peanuts to freelancing writers that don't know much about the subject, and the only "references" they give for the article is from Wikipedia and other similar blog posts. Since some of those companies have control over thousands of (seemingly unconnected) customer blogs, they can link from one blog to another (and from social networks) to increase their PageRank score.
Some of the larger ones are even starting to employ machine learning to write articles, so expect even less quality from now on.
And Google doesn't care for one simple reason: search keywords captured by Content Marketing blogs are worth way more as AdWords.
They pay peanuts to freelancing writers that don't know much about the subject, and the only "references" they give for the article is from Wikipedia and other similar blog posts. Since some of those companies have control over thousands of (seemingly unconnected) customer blogs, they can link from one blog to another (and from social networks) to increase their PageRank score.
Some of the larger ones are even starting to employ machine learning to write articles, so expect even less quality from now on.
And Google doesn't care for one simple reason: search keywords captured by Content Marketing blogs are worth way more as AdWords.