I'm primarily a dirt fan, but I understand Petty's point of view. He lived through the process of NASCAR leaving behind the grass roots dirt tracks for larger paved speedways, and at the time the distinction was important to elevate the series into something more distinguished and "professional", as he says. He apparently hasn't kept up with how serious and professional dirt racing is now, but I don't expect him to have.
I just turned 42, but even I remember the mindset in the '80s when dirt tracks were being covered in asphalt because it was the future. Times have changed, and now top level dirt racing is as or more prestigious as top level short track pavement racing. With the cry for "more short tracks", this leaves NASCAR with a resurgent market of dirt racing that they are trying to tap into.