Dare I suggest, based on those eloquent tales, that Con Pilot and Mach E Avelli are describing two different types of incompetents. One is, with the best will in the World, just not that great at what they do. The other lives in a strange half fantasy-world in which they cast themselves as hero.
They crop up in all walks of life, not just aviation and I (like most I would guess) have seen my share of both types. However it has always been the delusional type that I have found the more unnerving - usually because it can take quite a bit longer to spot than the simple incompetent.
In the normal way of things, dealing with these people is just part of life. However the idea of either of them getting command of a passenger aircraft is quite scary. Thankfully the tales of Biff and Bob had "happy" endings. But how likely is it that there is someone like that actually in command of commercial flight at this very moment?