none of the classic artists would of made the grade if that show was around back then it would all be the pretty boy and girl bands with their bubblegum pop just like it is today.
Talent and charisma can show through on those shows if the contestants have any (most do not).
A better question is whether The Stones would have appeared, or avoided it like many artists now avoid Idol. Idol is for losers who don't mind being humiliated, not for serious talents or song writers. Nothing but manufactured hype for making a quick buck for the next year. Most disappear quickly after their 15 mins of fame. Of course, The Stones did Dean Martin's show and got humiliated, but that was a one time deal.
Maybe someone could check out the 'talent' gauging shows of the day and see how Stones songs faired in say the American Bandstand 'rate the record'. That's the way you did it in the sixties.