Well, just about all new cars use an electric fan these days, so what's happened? First, alternator efficiency is up from 50-60% 20 years ago to >80% today. Capacity is up too, a typical new car will have a 160 to 180 amp alternator as a minimum, that's nearly double the Supra, and it will have the wiring to match. Also, reliable power electronics allows variable speed fans to control noise and reduce electrical load.
When you put an electrical fan into a MK3, it's never going to be properly engineered for the reasons above. You are adding 60% more electrical load without doing anything to compensate on the supply side. Stuck on a Los Angeles freeway in summer with the engine idling, AC on for two hours you will likely drain the battery dead. Also, the inefficiency of an alternator with 50% efficiency driving an electrical fan motor with 80% efficiency means that mechanical fan setup is going to be putting less load on the engine.