Those articles are copy/pasted from somewhere else, and part of the problem is that genuine users aren't taking the time to check out the content or the user it came from before hitting the upvote button.

it is actually very easy to do a reverse search on text to see if it has been used elsewhere, but it gets harder when the cheaters take an article to Google Translate and change it up. In fact, that's what the @cheetah bot and @steemcleaners are there for.
Plagiarism can be fought, but it's a never-ending battle.