Not necessarily. As you mentioned, the brothers Chmerkovskiy are a fan favorite. Val's dance was very emotional. So he & Alfonso could split votes, leaving Duck Girl with the most votes for the win.

He was between 6-12 at the time. And he had one or two short dances in the show. Although the show was named Tap Dance Kid, he wasn't the main star. It wasn't like he was Michael Jackson, inventing the Moonwalk.
I'd say a good portion of the stars who've made it to the finals have had dance training as a
kid. Jane Seymour was actually a professional ballet dancer until an injury made her switch to acting. She didn't make it to the finals. IMO, I don't think dance experience necessarily correlates when they are adults. Although they may be more graceful and have better rhythm because of it. I think it depends on the
kind of dance experience.