Interesting hypothesis, but it doesn't hold up to even cursory scrutiny. The most obvious counterexample is that the foreign state actors (not China but others) could successfully suborn and control several of these niches, and steer the groupthink of these groups in a direction favourable to themselves: Most obviously the take-over of the NRA in 2015 and the successful influence campaign on the "gun nut" niche by the Russian state; but there are countless other examples.