Well, it reinforces the hypothetical argument that sites like this have a mechanisms whic promotes settling into some kind of self-reinforcing content patterns. You’d have to actually show what the common patterns were for each site (and particularly whether they were share substance of argument or shared style, or both) to make the “groupthink” argument.

(I think the best argument against the groupthing argument here is how inconsistent the positions are that are claimed to be the “groupthink” position by those claiming that.)