Even worse, it tends to go hand-in-hand with astonishing overconfidence in their understanding of other fields. I've had two other primary careers-- designer, and chef-- and I can't count how many developers have "explained" parts of those fields to me despite knowing I'm a subject matter expert. Like their astonishing intellect and that related Metafilter thread they skimmed makes them authoritative. I get supernova-intensity cringe when I hear other developers shoot off Dunning-Kruger-esque oversimplifications of other fields' genuinely hard problems.
When I hear developers talk about the arrogance of designers, I can't help but laugh... then maybe cry. Many seem genuinely aggrieved that interface designers have more input on the interface design than they do.