E.g., suppose the defining trait of group D is: "always reads the entire article before posting a response to it." If Groups A, B, and C do not possess that trait (and judging by HN, they may not) then the benefit of group D even becoming a supermajority by harping on A, B, and C far outweighs any contradiction in their counter-culture identity.

On the other hand, if the reason for group D existing is to simply reject any position held by a majority of citizens, growth of group D could be detrimental to democracy.

In the first case, group D harped its way to a better society.

In the latter case, group D harped its way to a worse society.

In conclusion, your truisms don't say anything meaningful about the potential creation of another social signal.