Dobro and G maj13
No bar position in GBDGBD spells G maj13.
G maj13 spells G – A – B – D – E – F#, but the dobro chair has no bar for it: at every fret of the GBDGBD neck, and on every short slant, the strings that land on its tones leave one out or too few of them ring.
In a country arrangement that is an ordinary night's work — the dobro plays the part of the chord the bar can reach, or a single-string line through it, and lets the guitar and the rest of the band carry the chord. This page draws no grip a steel cannot hold.