Conceivably, you could run trials by having a judge (or panel of judges) bring forth the evidence they thought was important. Instead, many countries have a system where one party prevents “one side” of a case and another party presents the “other side”. How did this come about?
Actually, to my understanding, the two mains criminal justice system are either inquistorial with a judge over-seeing the investigation (in both direction) and transmitting the whole case to another judge for the trial and indeed adversarial. I am pretty sure full books have been written on the pro and con and both system