So is one implication that people who interact with non-representative populations systematically reduce their effectiveness in dealing with outsiders via inappropriate counter-signaling? Seems plausible.

My example is the possibility that advertising has become less effective with time because the advertising specialists have to signal their cleverness to other advertisers (who have seen a lot of advertising and who are very sensitive to it) to get the job. They show this cleverness by making advertisements which are too subtle for the consumer audience to 'get'.