Having spent about 15 years doing concert photography, and having attended about 500+ shows, I can say for certain that bands that use guitar amps for their backline always have the worst live sound. Being in front of the barricade/front row to take pictures totally would kill my ears when someone would have a 4x12 with v30's. Those things were blasting an icepick tone right at what is my head level (depending to some degree on the height of the stage).
Its one thing to have a loud cab flapping your trouser leg, when your ears are about a good level higher, but from the audience position its ice pick city, unless your out of the line of fire to the side of the stage.
Pretty much every show I've been to, has been loud and harsh sounding, with the exception of some smaller trio types where its thing like upright bass, soft hitting drummer and a guitarist playing something like a 1x12 combo amp. No much in the way of "volume wars" in that setting.
Whenever its more of a rock band, its one guy with a 4x12 who thinks he has to crank it, to match the volume of the drummer, or the other guitarist, who also is cranking his rig, because again, the off-axis listening might sound good, but someone, somewhere is getting the on axis sound. Then the vocal PA usually can't deliver a clear tone when its cranked to compete with a 100watt amp and 4x12 cab, so then the vocals are too loud as well, and essentially the whole show is just loud, but not clear, full or rich sounding.
Compare that with shows where bands run ISO cabs, or IEM's and a silent stage. The whole show, with proper instrument mixes, is running through the FOH, which has a much better spread, and can tailored to the venue. Sounds so much better, its loud, but full, and clear, with no harshness. No icepick in the ears. Totally more enjoyable.
IMO, every band member should have IEM's, or just use a wedge. Given wedges vary, many enjoy using a FRFR for this purpose.
You can use a FRFR like a CLR for a backline I suppose, but I for one don't really see my CLR, with its 1x12 speaker, really as a tool to deliver sound to the whole venue. Its for my own stage monitoring, as I'm not a fan of IEM's.
In a perfect world (for me) every band would have a decent PA, if the venue doesn't, and cabs would be mic'd, or better yet, use load boxes and IR's, and all the house sound would be delivered with proper mix through the PA system.
Using an Axe-FX just helps avoid issues with carrying amps, load boxes etc, as the entire rig can plug right into the mixer.
Then its as simple as using a house wedge, bring your own monitor, or use IEM's, to have a custom monitor mix hearing yourself, and the rest of the band, at the levels each member wants.
Its the end of volume wars