I think that years of this implied inadequacy have a residual effect on a guitar player's self-confidence, which helps explain why so many players overproduce their recordings, and bury their true essence. The availability of multi-track recording is the other temptation. You go in the studio, sing a song you usually play solo, and when you listen back to it, you may not be happy with it. This could be for any number of reasons. It might have been just nervousness.
Performances are delicate.
It might have just not been a good performance. Obviously, this song needs something else. Maybe it just needed to be played better. Maybe the guitar part needed to be reworked. Maybe a different tuning or a capo.