George
What's an accomplished guitarist? Here is my answer: it's a person who can do at least as much as the bare minimum required by the musical situation in which he finds himself. Who can do it cleanly and consistantly. A nice to have is the ability to rip out an improv if needed.
That accomplished guitarist should be able to express himself on guitar and get some of that emotion out of his system. Some cover band guys (I played with two recently) can have problems with that after getting used to ALWAYS do other's songs. Not all though - some of the guys on this forum do covers but also keep their creative hand in as well.
People who play covers a lot have a big advantage in some ways because they all know at least some of the same songs. I'ts unlikely you or I will meet somebody who knows how to play our originals.
My dream situation has me as bass player with switch offs giving 20-30 percent of the rythym / lead work to keep my hand in. I just get a bit uncomfortable it's not me on bass!
I've really come to love playing six string guitar. I'm good enough now to play it with people, at least with tunes I've written. Barely. And for now I have to so it's pushing me hard.
Get better every day though. And I bet you do too!
Talbot