As an (evidently) old school lover of live music, I couldn't agree with this more. To the guy complaining that his phone is "his memory": maybe that's a sign of a problem rather than justification for your behaviour.

Live music is ephemeral. That's its nature and part of what makes live art of any form special: no one will ever duplicate your experience. Trying to reproduce it with some crappy cell phone recording is hopeless, so why waste time, while squandering that experience, by trying?

Add to that the fact that you're interfering with the enjoyment of fellow concertgoers (yes your cellphone screen is, in fact, bright and blocking my view), and I'm all for this.