Wrong, Patrick Wolf pwns at everything.
It DOES make you talented, especially if you're good at each, which he is.
He plays drums and bass too, and Conor Oberst is a fairly average piano player, below average he can play the few songs hes written (When the Curious Girl etc) but as revealed by the Saddle Creek video not very well (he messes up the intro several times). I don't know why you brought him into this, I don't think much of him as a musician, theres better acoustic guitar players (John Fahey, Phil Ochs, Elliott Smith, Nick Drake) but hes a hell of a songwriter.