This is where I want to remind you, Stackoverflow is a Q/A site that sometimes contains stolen content from, as you put it, so-called "content farms" and the official resources.
Now, I do have a Stackoverflow user as well, but I actually prefer publishing my ideas on my own site rather than help build someone else's content farm for free. Stackoverflow is, itself, a content farm, and it can be very hard for new users to join the site. You can not even post comments without first earning enough points. For a very long time I would actually resist joining the site for that reason. I have only recently earned enough points to comment.
Now, I happen to own a so-called "content farm" too, and the choice can either be between creating a standard blog with very little traffic or try and cover everything you can possible think of in order to compete with other "content farms" in your niche. It is very difficult if not near impossible for a single individual to create a valuable resource and maintain it, and it is simply not sustainable if you have paid authors working on it as well. There is no way you can monetize it decently. Stackoverflow probably found a way around this problem by simply leaning back and monetizing their users content.
Once your site grows big enough, you also deal with a ton of spam- and hacking attempts. Everything combined just requires an inhumane amount of time to deal with.
Of course, authors are desperate because of how difficult it is, and perhaps especially authors from poor countries that might not have other sources of income. Their basic business model seem to be: create a content farm with ads, fill it with copy-written spam and hope Google indexes. Often these sites even have multiple authors, which is quite baffling given the extra expense it must create for them. But I do not think they have actually thought the idea through – because it is just not profitable.
Weirdly it's often in the technology niche, which they are clearly not proficient in, and more or less containing stolen solutions with little original content added.
I have seen a few sites like this, ripe with some of the most nasty grammar too. It interesting they are able to rank simply based on their volume? Of course they must be using blackhat techniques, including linkbuilding if you analyze their link-profiles, because there is no way that something so poorly designed and maintained is getting that much attention compared with official sources or stackoverflow.
For those of us who own blogs, such sites are often easily outranked simply by writing a comprehensive article on whatever tiny topic they have posted about.