At a pub i used to manage we had a nationally well known band playing. They had a reputation for being pretty loud but the volume was just ridiculous. To give some perspective, I was a roadie for one of Australia's best known bands in the 80's who were known as one of the loudest acts in the country in their prime, but they rarely played in a medium sized room at anywhere near this volume. I had to refund at least a dozen people after the first few songs and probably half the audience went into another part of the pub to get away from the volume.
I never say anything to any sound guy unless I know them personally but this one time I had to break that rule. When I asked him if he could bring it down a bit he simply muted every channel except the vocals, kick and snare and shrugged as if to say "sorry, can't do a thing" ...... and the volume basically didn't change. It was just their stage sound that was so stupidly loud.
I have fought this battle many times as a sound person. The venue manager/promoter/buyer comes over and asks if I can bring it down a bit and I do exactly the same thing you described above.
I've told this story before but I was mixing Buddy Guy in a theater in Orono, Maine many years ago and they had a strict 95dB cap at FOH position. Well, just before soundcheck Buddy came out on stage, his tech handed him his guitar and KERRANG!! the meter at FOH hit 105. The manager of the theater and several other people came running to tell me I had to turn it down. I told them that I didn't even have the PA turned on and that it was all coming from the stage. The manager very seriously told me that I had to go up and tell Buddy freaking Guy to turn his amp down. I laughed and told him that if he wanted Buddy to turn down then he could go tell him himself. I think they tried that and were basically told to pound sand. An hour later they came back with a letter permitting us to exceed the SPL limit.
That said, as a veteran of the audio business, I don't think shows are any louder now than they were 20 or 30 years ago in general. There were plenty of excruciatingly loud shows back then too and lots of terrible mixes. If anything, my (totally anecdotal) experience is that the percentage of good sounding shows is actually increasing. I've seen a bunch of heavy bands in clubs recently (Baroness, Clutch, Mutoid Man, etc.) and they've all sounded great. Loud but not excruciating. Nice clear mixes too.