There are very few BJJ purists left.
However there are still a number that are almost pure JJ fighters that still compete and do well.
Guys like Mario Sperry,Renzo Gracie,Wallid Ismael,Matt Serra,Antonio Nogiera(allthough he has good boxing skills).
BJJ and wrestling are the 2 styles that can get away with the least amount of cross training.
Obviously the best cross trained fighter will beat the purist on most occasions.
"You're Good Kid Real Good,But As Long As I'm Arround You'll Always Be Second Best See".