When dozens of celebrities offer to work for free, they won't pick a nobody. So what are you trying to prove? Do you honestly think it wouldn't skyrocket a new performer's career?

I think it sounds like an example that doesn't prove what you aim to convince me of.

The goal was to disprove "this sets the standard that work is worth $0". And celebrities using it in the middle of successful performance careers seems to disprove that idea just fine.

You're the one that brought up breakouts, but the part you're demanding proof of is something that's obvious. No, I don't have proof that a nobody performing in the super bowl would have a huge spike in popularity. But I think you're being ridiculous if you think that wouldn't happen. If you want to find a flaw in an argument, demand proof of something that isn't obvious.

At best we can say it doesn't hurt some of the best-known and most popular performers in the world. If you're the Beyoncé of your field you can do whatever and it's unlikely to hurt you that badly. That has little bearing on the current discussion.

Willful ignorance is not a good argument. These performers have detailed public sales figures. We know with certainty that performing in the Super Bowl is a large boost to their sales.

But their business model is totally different from a photographer. They're not in the business of works for hire and are featured far more prominently in the show than a photographer is going to be in wedding photos. I just don't see how this example is relevant.