My point was that Sony entering the film and music industries, which happened in 1991, soured their relationships with the other studios and labels. Compact tap

My point was that Sony entering the film and music industries, which happened in 1991, soured their relationships with the other studios and labels. Compact tapes predate that by several decades and CD and 3.5” discs both do by 9 years. Clearly Sony had no problems getting their media formats adopted before that strategy shift. After that they had to fight tooth and nail.