The way I learned guitar: 1. Lessons for 6 months, didn't learn much. 2. Started playing cover tunes, did that extensively for years. Practiced by butt off. Played with a lot of different people. 3. Went back to learning theory. For me my main motivation to learn guitar was to play in a band, not to become good at the guitar itself. But it turned out that I was talented enough to learn a lot by just screwing around.…
I agree, but if the guitar is someone's first instrument it may also be their only creative outlet or seen as a means to an end. They're almost guaranteed to do what you did and probably even skip the lessons.
I think the physical act of playing an instrument is very overrated, and music education is underrated. Even just a few years of putting kids in the school band goes a long way. Being familiar with sightreading and basic music theory sounds boring, but it makes everything else a breeze when they want to learn something on their own.
Of course, there are also tons of people who were in a bad program and it was worse than nothing for their motivation. That's another topic though.