Bishop > Rook might be true in the opening if you look at the instantaneous tactical power. But most pieces will survive into the late middle-game, where the value will reverse. So the Rook, even when pretty useless, has a lot of 'latent value', which will be realized automatically as the game phase progresses. This is especially true if both players have approximately the same latent value; then the difference in instantaneous tactical value is not so large that the game can be decided before the latent values are realized. For this reason piece values are usually dominated by the end-game values, and starting with a Knight instead of one of the Rooks is an almost certain loss. It might be different if one player had 7 Rooks and the other 7 Knights, although even then I doubt the Knights have so much instantaneous advantage that they could quickly decide the game. The Rook might not have much offensive value early in the game, but it can still be useful for defense. 7 Rooks + 1 Pawn would probably lose against 7 Knights + 8 Pawns, though.

In games with piece drops, like Shogi or Crazyhouse, you basically are in a permanent middle-game situation, and the instantaneous middle-game values become relevant. Indeed Shogi players value Rook and Bishop about the same.