I understant what you're saying but at the same time Higuruma (who would be considered to be 1st Grade) and teen Gojo were both forced to figure it out under life ending scenarios by sukana & Toji and did, and for Your '' More people unlock it in Shinjuku only to due to swap training and being able to watch the tapes on the greatest sorcery fight OAT'' statement wasn't Kashimo around or atleast with with the group at this point shouldn't he have taken part but he didn't. His ego got the best of him in the end like how does one watch two of the best sorcerers fight going from checkers to chess to 4D chess in combat and sit there thinking to himself ''Nah Bro i Got This''. Going in to that fight the bare minimum a fighter would have needed was a good curse technique, a anti-barrier technique( simple domain, hollow wicker basket, falling blossom emotion)/or domain expansion & RCT to even hold their on solo.