A string quartet consists of 4 tonally adjacent instruments, and is thus much more like 4 humans talking. A "classical" rock band consists of 4 utterly differe

A string quartet consists of 4 tonally adjacent instruments, and is thus much more like 4 humans talking. A "classical" rock band consists of 4 utterly different instruments from a tonal perspective, and is thus nothing like 4 humans talking. Same thing for jazz - and its why you can have multiple instruments performing simultaneously and in ways that are not obviously connected to each other.