At no point did the CMA Awards say, and most certainly didn’t decree anything to the artists performing on the evening. In fact the statement wasn’t even directed toward performers at all, but at the potential audience. It was simply a piece of promotional copy intended to get people to tune into their event.
Music is not a skills competition. This isn’t the decathlon. They don’t hand out Grammy Awards for the band that can play songs from the most genres. They give Grammys to the artists who steady themselves and prove they are the best in a given musical discipline. I’ll give credit to the backing band of Weird Al for their alacrity. With the Zac Brown Band, I just want to hear good songs.