The Adams lab isolated CBD and CBN in crystalline form, made pure d8, other cannabinoids, distilled from ditchweed extract and also made somewhat pure d9, and knew THC was THC. He did not know which isomer the THCs were, where the double bond was located. That is all. Everyone's guesses were wrong.
Gaoni and Mechoulam had GC, NMR, police providing hash. Where they excelled was NMR interpretation - a new thing - matching data to physical chemistry theory. This plus chromatography allowed them to say when products were pure and what the structure is.
I read that Adams got red oil from the Treasury department, where he isolated several compounds like CBD.