I have read "put your phone down, I cannot see" and "It is distracting" Seriously if you cannot see past a 3" wide obstruction you have issues, whine whine whine. At the last concert I attended, it was sold out, Loud music, loud Crowd, no phone noise I could discern, even the fellow next to me talking on his. The singer stated "Stand up, sit down, whatever you want, you paid for the ticket, feel free to use your phones and record or stand the whole time, enjoy the show" The whole time the crowd stood, from my standpoint it was a pain since the fellow in front was a bit taller but I didn't care, I was enjoying the music. Phones, people and even crying kids did not distract, I was there to have a good time and did. Every ticket has an admission price, if you want to have a better view, pay for a better ticket.
As reference the concert was Garth Brooks. Similar story with a Monster Jam event with my kids. Phones are not the issue, people are.