I am probably somewhere in the middle. If your roof is okay, don't coat it. If it's getting older it may need coated.
I have found that by coating the roof, I don't get nearly as many black streaks on the side of fhe RV.
I'm not familiar with RV Roof Magic. I have used Heng's Rubber Roof Coating. It does not need a primer, goes on easily and holds up well to the Pennsylvania summers and icy, snowy winters.