No one back in the 70s ever referred to the frisbee as a disc when we played frisbee golf. Disc golf is what those later to the party called it.
Frisbee is proprietary trademark of Whammo.
Whammo doesn’t even make the highly refined discs used now in the sport
Back in the 70’s we were throwing Frisbee’s, the disc’s look nothing like nor do they throw like the Frisbees of that era, you don’t want to try and catch one.