At a certain type of design-centric company the culture shifts, and divas are both created and elevated to a degree that you don't see elsewhere. Most companies don't tolerate that sort of artist/designer because they're obnoxious and generally horrible people (and they don't work well with others so unless the culture is one that prioritizes them over everyone else they tend to flail and fail pretty quickly) but here and there you'll find pockets where they thrive.

I think you're absolutely right that in general artists are not like that. It's a few bad apples, and for the most part they don't ever have much opportunity to do damage because it takes an exceptionally weird company to enable them.