I'd taken a step back but I'll bite.
Here's some view points to consider.
Plenty of people go to a gig, or festivals to "see" bands, yet still have obstructed view of the stage due to people's heads... or in some cases, end up watching the show via big screens alongside the stage. Would make for a pretty poor experience if the sound was pants too.
For a lot of artists, it's all about seeing the spectacle of the show but it's a given that the sound has to be good also. You may recall the media couldn't wait to rip into the Spice Girls when there were complaints about the audio. Seeing the show was not enough. And you could argue that the audience were a home crowd and not exactly your audiophile audience.
Plenty of people have been to gigs where the sound as been horrible... and it's always the sound mans fault for doing a stinky poo house mix. In reality, the sound guy is an important member of the band - even if they aren't on stage. They can make or break your sound. If somebody wants to come on stage and run an amp so loud to get "their sound" and feel good, so be it. After all, they are the talent. However, ultimately - and this is the science here, you are going to get bleed into other microphones and the mix will suffer. How much depends on how much of those little nuances that impact the mix sum. So yeah, there's so much you can get from baffles, correct mic choice and placement, monitor wedge volume etc... I get that you won't get a CD mix in a gig situation - but as an audience member you do want to be able to hear things clearly - and you don't want to have that lone guitar cab overpowering the front of house speakers. Or perhaps you do. You'd hope that an artist would want to sound the best that they could out front, even if it means compromising what you want on stage - after all, it's the audience that are paying your keep.
In reality, it's about the right rig for the right gig. If you are playing a small gig, you have to compromise with the backline you are using to work with the sound guy to make you sound the best out front. If people don't want to sound the best out front, why are they even bothering? It's a certain arrogance of artists that has always been entertained for so long.