Why the extra rank on each side in 4 player chess? Why do we have an extra rank (the red lines below) on each side in 4 player chess on? What could be the possible logic? 


(screenshot is taken from chess.com)
As SmallChess notes, the rook pawns would be able to capture on the first move. That in itself wouldn't be a problem, since the player can just capture back, but then we have a situation with two half-open lines where the pawns are pinned against the rooks behind them. That's a lot of tension already after the first move, and on the flanks, which is quite rare in normal 1v1 chess.

I'm not sure how to visualize this, but if red takes the blue pawn, and blue responds by capturing with their rook, yellow's king's rook pawn is pinned by the red rook (and attacked by the blue pawn) and green's king's rook pawn is pinned by the blue rook (and attacked by the red pawn).

@RemcoGerlich notes another very early possibility for two players to gang up on the last player, by capturing two of their pawns on the first move. Perhaps this is part of a general problem with 4 player chess...