That seems more like a conspiracy theory. I think the group of people who 1) view this website and 2) click on a thread about certain topics are a heavily conditioned (and therefore more homogenized) group; if you say something that is controversial/low quality, it is likely going to get downvoted by multiple people in that group.

Controversial/low quality are both subjective and i am not a fan of putting controversial next to low quality.

I do agree I dont think there is any larger bias other than a homogeneous group but it does question if such a group will up/down vote similar homogeneous content producing overall lower quality discussion and content.