less than 1% of people are negligible, it could be a fluke in team building were they forgot it, or they are just stupid to be quite frank.
Heatran should never be on a rain team... ever, and Scarf Dragonite is kinda pointless, especially with the rock weakness. On a rain team Keldeo or Tornadus would be a better replacement or use Choice Band Dragonite.
I am not Scarf Wynaut on Pokemon Showdown. I am PrincesoBubblegum