It’s fun. Plain and simple.
edit and drifting is more of an exhibition than a competition in japan. Yes they have D1 but their main goal is to entertain the crowd, not to win. That’s why you don’t hear “The number 1 D1 driver” or “the reigning champion” you just hear “D1 driver.” It’s about fun and entertainment. You don’t go to a concert to see which band member wins, you go to enjoy the show.