Whilst many commercial games were machine code they were still technically underwhelming due to ST-PORTING-ITUS!
Knowledge of chipset quirks and how to use blitz mode properly are just as important IMO.
Personally I have yet to see an OCS game I believe uses 100% of Amiga, except maybe Lotus II on NTSC machine. That sort of quality definitely requires ASM AND skillful exploitation of Amiga features/quirks, a very rare combination.