No? Good cooks most definitely sharpen their own knives.
Most piano players don't have a clue about how to tune their pianos, though.
Most professional musicians know their instrument very well - and still know a man for the "hard" stuff, e.g. for thorough maintenance or repairs that require craftsmanship.
And there are obviously variants. The guys that fix their instruments regularly and experiment with e.g. cooking your stings, and musicians that hand them in for the tiniest, easiest tasks.