As a guitar player, I heartily agree. There have been a number of factors inhibiting the public’s appreciation of his playing, including, as you mentioned, the fact that he doesn’t play solos. As a Jazz fan, I think the McCoy Tyner comparison is a bit overblown but his approach to accompaniment is similar to jazz "comping" in that, rather than just monotonously bashing away at barre chords, he weaves together (often) non root voicings with intervals and single lines to create parts that are musical statements of their own and he’s developed the ability to improvise such parts on the spur of the moment. His approach has been a big influence on my rhythm playing.
My personal favorite showcase for his playing is the ’72 Europe tour. The album "Europe ’72" is a master class in great rhythm guitar in Country-Rock, Country, R&B/Blues and spacey improvisational styles. But then, that’s my favorite year for the band, overall. I love not only the material but also the band’s sound, dominated by Garcia’s strat, Weir’s ES345 and Godchaux’s acoustic piano.