Agree with that Howard: I only play in standard tuning, and learned guitar by chord shapes rather that actual notes: never learned guitar scales, so other than knowing the names of the open strings I couldn't have told you which actual notes I was playing. It was probably my piano theory and a bit of ear stuff that allowed me to put compatible chords with particular songs or tunes.
As a side issue to this, at a Trad music class I attend we were given a melody and then 2 of us took it away to put chords to (independently of each other): for the same tune, we came up with completely different sets of chords, both of which were agreed by others in the class to be perfectly acceptable interpretations: mine were fairly simple major I,IV,V with the occasional relative minor: the piano accordionist came up with a lot more minors, 7ths, "double sharping" etc - by his own admission "fussy chords". Then came the vote: 50/50 from the rest of the class! So we now play the piece twice, my simple chords first time, the more complex ones second time: nice arrangement, everyone happy!