The one extra benefit of having a basic understanding of theory is that you can converse with another musician and understand what they are saying.

If you can understand someone saying "It's in E, and just 1, 4, 5 for the most part", and know what that means for the song
Then you understand at least *some* theory.
The more you know the better you can converse (and thus learn), as with any language, like the other Bob mentioned.

It ain't necessary to have this in order to play well, but it sure makes the 'Learning' part of it all a lot easier, which was your original question I thought.




I do not work here, but the benefits are still awesome
Make your sound your own!