PCs and consoles back in the day used to have actual hardware synthesizers to play music. (Wild!)

Synthesizers are real musical instruments, so game designers actually had to compose and arrange musical pieces for them!

Today it's just pre-recorded sounds, nobody needs to actually craft special game music.

P.S. Having a dedicated synthesizer instrument isn't a limitation. It was a cost-saving measure back at the time, but it's a special separate custom chip that we don't get to have anymore.