We're talking about going to a gig here: there are many ways that people "enjoy the experience" which might detract from the experience of others: talking, singing badly, moving around too much, jumping up and spilling beer everywhere. If you try to eliminate all behaviour that might adversely affect others, we'll all end up strapped into a seat — no-one really wants that.
Playing with your cell phone is a lot less easily justified than singing bladly or dancing too wildly. If someone is talking over the concert or spilling beer on me I'm going to ask them to stop, too.
> Playing with your cell phone is a lot less easily justified than singing bladly or dancing too wildly
Taking a photo to commemorate a once-in-a-lifetime experience, recording video to show friends, checking the time because you can't stay until the very end, checking the babysitter hasn't called to say the kids are in hospital, ... there are many reasons I can think of that, whilst they may be annoying, and may to a very small extent detract from your experience, are still 'valid' and necessary from the other's point of view.
> If someone is talking over the concert or spilling beer on me I'm going to ask them to stop, too.
Right. I must admit, I wouldn't do that in the same situation, partly because I'm conflict-averse but also because it wouldn't bother me that much. However, I wouldn't argue that beer can't be served at the event or no-one's allowed to talk at all. I have no problem with you politely asking someone else to take their cell phone out of your face, but I see no reason why that has to result in a blanket ban.
>Taking a photo to commemorate a once-in-a-lifetime experience, recording video to show friends
Not okay at the expense of others. Professional photographers and videographers are likely recording the event for you.
>checking the time because you can't stay until the very end
Plan better or buy a watch
>checking the babysitter hasn't called to say the kids are in hospital
What are you going to do other than worry if you go to the hospital? What do you think people did before cell phones? It's OKAY to disconnect for a bit.