I have used primes – I’ve tried everything! – but because of the nature of live performances, it’s rare that an artist will stand still.
If they do stand still it will be fine to use a prime lens but if they’re moving then you have to be very fast because the lead singer might be jumping right in your face and the next minute they’re next to the drum kit.
To be able to work quickly with an artist, you have to be able to zoom in and out when they’ve gone and you still want to have a clear picture and zoom in, and when they come very close you have to zoom out.
So that’s why a zoom lens is actually the best tool you can have. I see a lot of photographers using prime lenses but they can’t do what I do because of the restrictions of a prime lens.