Can you name any self-taught violinists who are now concertmasters with a major symphony orchestra?
I thought about violin, since I used to play it and I purposely left that one out. I believe it's one of the hardest instruments because the cost makes it a bit prohibitive both for the actual hardware and lessons. Also proper form is rather conducive to consistency, and improper form is easily noticeable. And finally, classical violin might be considered one of the "higher class" instruments as opposed to say a tin whistle, and the audience, conductor, and whoever is the gateway to your achievements would care about proper form or appearances. Jimi Hendrix however, held his guitar upside down.