Last night a friend took me to a bar with music so loud we couldn't hear each other shout! How and why did this become an acceptable industry standard?

The question assumes blasting music is in fact an industry standard, but... come on. I've been to a lot of bars, and many are like this. I have to assume that bards at medieval taverns or ensembles in fin de siècle dance halls were not bringing down the house to this degree, and it had something to do with the modern transition to nightclubs. But the fact remains: who in their right minds asked for this? Why did it become so common?