I have read much of Stephenson, including The Diamond Age. Maybe I got the observation from there, but I like to think I noticed it independently.

The place I've noticed this tendency most strongly is Private Eye. This is an organ that you wouldn't think of as a bastion of relativism, but they are particularly keen on stories which contrast someone's shameful deeds with their own pious words. Perhaps it's fear of libel suits that means they avoid direct accusation; or maybe the writers believe it's makes for more effective satire to have the accused condemn themselves with their own words. But when the tactic is used week after week it starts to give the impression that the fault being criticized is purely the hypocrisy of saying one thing and doing another, and if only the person had got their story straight they would have been fine. (An example.)