Yes, it can be a bit crushing when you think you are entertaining an audience and out of the corner of your eye you notice that somebody is more concerned with their phone.

However, you can't force people to concentrate, and so long as they are not making a noise or a distracting light in a darker venue, then no problem really. Might be confusing as to why they are sitting there at all, but perhaps it can be comment on your song, so a subtle hint such as this can be a good thing...

I keep most of my lyrics and info regarding keys and styles on my iPhone, as well as a tuner. It also gets used to record things occasionally.

One question being asked a lot here, is the old "What did we do before them?" Quite. For me, there would have been evenings when I couldn't get out to enjoy myself but the communication a phone gives allows you to. Many work related evenings spring to mind. I had a mobile phone back in the brick days and they helped me enjoy a night out knowing I could still be contacted if necessary. Once silent vibrate came on the market, then even better.

I recall one monologue performing gentleman many years ago who used to sit in a folk club reading a novel between his "turns." That was ignorant too, so perhaps you should ask if ignorant people rather than their props have no place at "your" festivals?

I am surgically attached to my phone and have been since my first car phone in 1988. For me, not having it in my pocket feels strange and something is missing. I don't play games on it period and I don't use it without good cause, but if it vibrates I will always at least check to see if it is urgent or not.

So the answer to your question is Yes, they do have a place at festivals because I go to festivals and I take my phone. You may wish to ask questions over ignorant rude people themselves, but removing one item of distraction will only result in them finding another...