Are you an economist IRL? I know economics jargon when I see it! Lol
But regarding the OP. I'd say I've seen a fair amount of dropping by all roles, though I may not have had the exposure others have had due to both tanking and healing being my mains. I'll admit that I've dropped a handful of times because of rude players, but I have no issue explaining to newbies - I was there once and I'm always appreciative of others who help/explain mechanics or have patience with newbies as well.
I don't think tanks should be pigeonholed like this, we're not all bad. It's probably more on the player than the role. Someone who is easily frustrated with new players or wiping is going to quit regardless of whether they're tanking healing or DPSing.
