Just because 100% of the audience is capable of using wifi doesn't mean that 100% of them will be using it simultaneously.
Tickets cost a minimum of $2,000 on stubhub.com for nosebleed seats.
This event only happens once a year.
People really want to see this thing live.
With a drink in one hand, popcorn in the other, and a smile on their face, I would be surprised if more than 10% of the audience was glued to their phone at any one given time.