He didn't say that you handicap. What he's saying is why go to a concert just to hear yhe same stuff you will hear on YT, the only difference is the anime chick is projected on a god dann wall.
So you can experience it with other people, with the light-shows, the loud music and the numinous feeling of it all.
Have you ever been to a concert or music festival and listened to live music on a stage?
It is completely different from listening/watching it at home. You get taken up into the whole atmosphere of it in a completely unique way, regardless of the band/performer.
You're only picking on this fact because it's got a holographic image playing as the singer.
People don't exactly question why anyone would, say, go and see the Red Hot Chili Peppers play live, when you can just watch them play on YouTube. But that's the equivalent of what you're getting at.
Sounds like it'll be great. I hope you thoroughly enjoy it!
I personally would probably prefer to see Lady Gaga, since I do like her music. Her eccentricity is a bit annoying, but I like her music enough to put up with it.