Self taught is a misnomer. I know what we mean when we say it, but in truth we do not learn anything in a vacuum. Somebody else is always involved, usually a friend, but bandmates, snooping around music stores (folks are always doing this at the local shop), transferrable knowledge form previous lessons on other instruments and school, and so on. We digest it, poop it out, and spread the compost on our creativity.
My own experience by some descriptions could be characterized as self taught because I never had a formal guitar lesson (until I attended workshops by the likes of Pierre Bensusan, Don Ross, John Renbourn, Simon Mayor, and others long after I'd started teaching others) but in fact all I was doing was applying several years of formal piano, choral, and voice lessons to the guitar. Before I could tell the difference between a guitar and a ukulele I knew major and minor scales and arpeggios, chord construction, harmony, etc so laying it all out on the fingerboard was a matter of mapping the thing. Technique was an early issue, so I watched the bands that played high school dances and picked the players' brains, hung out with friends who played and picked their brains, started jamming with guys and picked their brains, hung out at music stores and watched the better players and picked their brains (John Till caught me staring at him, I didn't know it was him until weeks later, and he showed me a couple of things), I happened to meet the secretary treasurer of the local musicians union as he was acquainted with my parents and he let me pick his guitars and his brain. Guitar Player Magazine in the '70s was great, but it was the only readily available modern print material.
I owe it not to being self taught but to every generous soul who allowed me into their sphere, my piano teachers, vocal coaches, choir masters, buddies, and complete strangers. I've been paying it forward ever since, even as I make my living teaching music.
All of this may well be more important and effective than some formal lessons, but as a product of formal lessons in other realms, I would have killed for private guitar lessons. In the small town of my teenage years their was no private guitar teacher, the nearest being a half hour highway drive away and I with unwilling parents. It could have saved at least a couple of years of screwing around, especially early on. Initially didn't know how crappy my guitar was either!
In spite of adapting to the situation, and being reasonable successful under the circumstances (and maybe I kind of romanticize it all now), what I feel I lost by not having private lessons:
1) proper introduction and development of classical guitar technique,
2) suitable repertoire in the right order,
3) exercises to overcome difficulties in fingering,
4) proper posture,
5) concrete goals in order of difficulty and ability,
6) timelines for achievement,
7) proper explanation as to why all this was important,
8) encouragement,
9) time (so much wasted time in self instruction),
10) likely other stuff I'm too tired to remember right now.
I will agree that it would be easier today with all the materials that are essentially free on the net, but many people can't even apply information they're given without assistance. Between learning issues and personalities, there are too many variables to assume anyone can teach themselves music.
