This is just a guess, but I suspect many of the short-changed performances have to do with song rights.
I don't know about the rest of the audience, but I tune in just to see the performances. This season seems to be even worse than usual with the long and pointless sob stories. Don't waste my time if they're not going to even be on the show. I honestly don't care if her dad died of cancer or how hard some other dude worked but hasn't made it yet. Just give me some awesome singing and the coaches being charming.