This is absolutely rampant in the blackhat marketing world, (where I used to dabble, but still stay up on mostly out of curiosity).
The model goes like this: Watch a few different pages and try to identify something that's bubbling up - that can be different viral facebook pages, reddit, whatever... there are a few different ways, but basically you constantly ping and scrape and try to identify stuff that's going viral as early as possible.
Once you've done that, you have an automated script that downloads the video and uploads it to your Facebook page or scrapes the content and throws it on your wordpress site with a really weak "link back" to the original content. You build up a Facebook page that has a few million likes, cover your wordpress pages in ads, and profit. It's not incredibly difficult to create an automated-if-unethical Buzzfeed.
It's incredible to watch one viral post or video spread throughout the web. It spreads out on different sites and platforms as quickly as it spreads on social media. Few end users really care what the original source was (especially since it's usually click-baity BS anyway), and the winners are the ones who can find the content the quickest and have the biggest reach.
I talked to a guy a couple of days ago who is making $60,000/month using this exact process, and has very little programming ability. He is, however, an absolutely shrewd and ruthless marketer with no ethical qualms about much of anything.
The content producers send him DMCA requests on occasion, and when that happens he or Facebook takes it down. But that's just a cost of doing business, and 95% of the content stolen never sees a DMCA request, so who cares? (Assuming you have no ethical compass). Content creators aren't constantly searching and scraping and trying to find other places where their content is hosted. That's hard enough to do on one platform alone (i.e. YouTube), let alone monitoring other platforms (Facebook) and a bunch of wordpress sites.
It's a game of content creators vs. "marketers."
It gets even more difficult for the content creators as the "marketers" get smarter - heighten the pitch of a video a little bit so sound matching software can't find it, reverse the video and choose different thumbnails so reverse image/video searches don't find it, spin the text content (visitors aren't really there for the great writing anyway), and you beat the vast majority of software. It's up to the individual content creators to play the same game Google is playing to kill the spammers, which is not their core competency. Unless Facebook does something on its own platform, this won't change. And even if they do, the best spammers will continue to outsmart the system.
The only way Facebook (and the content creators) win is if it becomes a core competency, much the same way defeating spam is for Google. I still know guys who can beat Google, but the level of sophistication is high enough that 99% of people can't keep up.
There are a few simple ways you can beat the vast majority of the content theft though; if anyone is interested feel free to email me and I'll point out some of the breadcrumbs the marketers leave behind.