It's not a theory, it's a known and well-researched consequence of direct democracy
Well then they need to do more research because I have been on Slashdot now for decades I think, and I'm telling you how THIS SYSTEM works. Anyone can judge quite simply and easily for themselves by reading a large number of articles at the -1 level and see how many good but against the grain posts are modded down, vs. sheer and utter crap that no-one wants to see.
Not to mention that just like every time a complaint about "direct democracy" is trotted out, it's invariably against a system that is not a direct democracy. Not everyone can moderate all the time, and the moderation frequency is itself moderated in mysterious ways by meta-moderation.