I think he's referring to designers that make rather narrow-minded absolutist positions as an attempt to sound like an insightful thought leader and get fame.

An example would be the cliched idea that "all designers should code," where the reality is more in line with "it depends." This is of course discounting the fact that most designers outside UI design have little to no use of coding.

Jared's recently infamous "Everyone that influences the experience of something is a designer," also springs to mind as an obvious simplification of the world and a self-congratulatory message towards (UI) designers being the center of things.