Modern electronic sound enhancement and reproduction has killed liver performance, until one actually goes to see a really good show.
What has changed is that there is now little need for mediocrity. It used to be that even a mediocre painter could expect to find work, since his renderings may be the best his customers can afford. Nowadays, however, if an artist can't beat the work of a cheap camera and has no ambition of doing so, there's far less value in persuing it for anything beyond personal satisfaction.
Hepatitis B-flat?????
This was true during the era of "high-fidelity stereo records". It also imposed a deadening uniformity on music.
However, it seems that the Internet and cheap digital reproduction are loosening the grip of the recording companies. MP3s on web sites and short-run CDs published by the musicians themselves are creating more interest in a wide variety of music played in clubs and small venues.