In my experience the 0 bass setting only works on vintage fenders for the most part, my 69 twin has such a fat tone that the bass is booming if it's anywhere above like 2-3.
I would venture to guess that it was early 70's when Garcia started this, when he & bobby were working on separating their tones in the mix.
Something else I've found is that my best tone in a band setting isn't exactly my best tone when I'm home practicing. Garcia had it set like this to cut through the mix, a mix that already had more than enough bass & mids in it so in order to cut through he needed to be in the high end. Realizing that my settings just has to be different when playing in the band was a huge step for me & it's generally the bass that gets dropped for me. When I'm practicing I'll have te bass around 2-3 bc the tone can be piercing, but a piercing tone fits in perfect in a band setting. Allows me to cut right through the mix and sit on top. Rolling down the reverb is another thing that works the same way, by myself I add a lot more reverb and bass, but cutting through a mix is a different animal.