The drummer always starts the volume war. Way too F'ING loud, then the bass jacks up to the drummer, and I can't hear my amp on stage. So I turn up the amp, and the guitar gets all the blame. I say ban drummers.
I find the better the drummer, the more dynamically he can play. So loud or quiet, he can still sound musical. And of course if he's that good, he has no problems with tempo, although he still shows up late and/or wants to drink all our beer.
If I had an amp I didn't like the sound of when pointed at my head, it would be gone in a microsecond. If I don't like, why would I think someone else would? All the rest is just physics - if you want to hear yourself louder than everyone else, you need to be the closest person to your amp and it needs to be on axis to your head. Simple, really. And walk the room early on - hear what the paying customers are.