At a small music store that I worked at in the 70's I met a fellow who said he was a Nashville studio musician. Like barbershops and hardware stores, a lot of stories get "embellished" by guys at music stores, so I took his claim with a grain of salt. He looked the part with an expensive western cut suit, fancy boots, and a bouffant hair-do, but still.... But then he picked up a guitar and started to play boom-chuck, boom-chuck, etc. Simple stuff that any first year student could play. Pretty disappointing.
I guess I didn't hide my disappoint very well because he said, "You don't believe me do you? You probably know several guys who play better than me that couldn't find work in Nashville." He was right, of course, but I didn't say anything. I just tried to put on a neutral, diplomatic smile. He continued, "Do you want to know why they couldn't get or keep a gig? Because I can do this all day long and they can't play like this for five minutes before they start to gussie it up and throw in little extras. And you just can't do that in a studio."
That was the most credible thing he could've said. I remembered a session that I helped on a year earlier when I was asked to play a simple picking pattern on a single chord for about 20 minutes. That was hard - physically and mentally. Learning to play what is required is what a pro does. Showing off is what an amateur does.
I've always felt that a guitarist (or pianist, or violinist, etc.) is someone who chooses a song to show you how good they are. But a musician uses his/her talent to play a song in such a way as to move people - starting with themselves. Don't get me wrong. It's fun to get ahold of a song and unload once in a while. Or to accompany some other musicians when they take a lead, get inside the song and walk around some. But even then the player should be at the service of the song, not the other way around.
I suspect my opinion is in the minority, but that's ok. It's an opinion formed by a chance conversation with an older guy in an expensive suit and tacky hair-do forty years ago. And I honestly haven't found a reason to change it.