[Applejinx]

Interestingly, that used to be the rule rather than the exception… at the time when rock bands grew in importance to dominate the music scene and built an industry to sell their products to listeners.

Back when people went completely nuts for rock music, the PAs were generally so inadequate that they were just for vocals, and monitoring wasn't really a thing. Most gigs of the era ran off each instrument generating its own stage volume, hence the Marshall stacks and such.

The Grateful Dead famously scaled this concept up to insane heights with the Wall Of Sound system, where each instrument and voice had its own speaker stacks even at stadium levels. It really worked exceptionally well, but was cumbersome and didn't last that long.

This can be done in electronic genres, as well: it just isn't, for the most part. I daresay there have been sound installations that did it.