This is the case with ALL concerts. They were talking about this on the Howard Stern show a few months ago where some of the hosts attended an Eagles concert in New York. The young people in front of them seemed to not care about the music. They were texting during the show, taking selfies, and talking the entire show.
I never like to ruin anyone else's fun during a concert though. If you like to sing, go for it. But I also find it annoying when someone is loudly singing next to you. The only more annoying thing is when they loudly sing and don't even know the words
Flashback 1983. My first concert was the Wild Heart tour. Stevie thanked the audience for being so quiet during Beauty and the Beast. I wish I had those statements on tape but after the song she openly appreciated how respectful and quiet everyone was. Its common during songs like that were people shout out all kinds of things during the quiet moments of the song.