It's a little more complicated than being "too loud" though. The problem for venue sound is that everything is being projected from a single stereo source at the stage, meaning it generally needs to be at the very least 6dB "louder" at the source to reach the back row, and it usually ends up being more like +12dB for a larger venue -- due to both natural air resistance and bodies soaking up sound. So if it's a high energy gig and people want to dance, they need to be hearing it at a minimum of ~95dB (and we're more accustomed to over 100dB at this point), which means the front row levels may already be upward of 112 or 118, which nobody should be listening to for prolonged periods.

But that's just the average SPL. The bigger problem this all leads to, is when things aren't hard-limited properly and every single snare hit for the entire night is spiking to 130dB and over. It would be nice if it were as easy as slapping a limiter on the master and calling it a day, but it takes some pretty intense math to do it properly, because there may be dozens of speakers even in a small venue, and all of those sound waves are intersecting with each other and bouncing off walls and people. And that's presuming the venue was properly sound treated in the first place -- if it wasn't, then all of those compounding sound wave situations are made so much worse and unpredictable.

Ultimately, the problem is laziness and greed. Venues absolutely need to invest in supplemental systems to provide reasonable SPL at the middle and back, rather than trying to push it all out of two speaker columns on the stage.