As I remember in the liner notes of the CSNY collection I bought a number of years back, Nash wanted to play original music, wasn’t interested in doing covers so much.
As for being the glue, I’d have to give that to Stills. From my recollection, on the records, he played most of the instruments and had about a creative 18 months of writing songs as anyone has had in rock n roll.
Yeah, but that high voice of Nash...really meshes everything. Like Tomato Paste in a great red sauce.