I have a theory. I think that the REAL reason guitarists wrap their thumbs around the guitar neck so far that they are practically fretting notes on the low E string is so that their left arm doesn't get tired from having to support its own weight for long periods of time. I'd be curious as to what y'all think. This is something that I have struggled with for a long time (where to put my thumb) and still haven't figured it out. I once took classical guitar lessons many years ago, so I tend to want to do the "correct" thing, which is putting my thumb against the back of the neck, directly opposing the fingers on the other side.

And my theory includes one more factor. When you support your left arm with your thumb, it makes your fingers more stable, as though they have a point of reference rather than having to just hit the frets in the right places through the thin blue air.

But the reason I struggle with this so hard is that when I hook my thumb around the neck, I feel it greatly restricts the motion of my fingers, especially the motion of spreading the fingers apart so that they are far away from each other.

Thank y'all for your time in reading this!