Consoles typically have more than one controller, so they likely require a button press from a player to determine which controller that player is using. This way, no matter which controller each player is using, after the game loads you can determine who to consider 'Player One' by asking them to press a button.

PC does not need to do this because there is only one player and one controller: the mouse/keyboard.

Consoles typically have more than one controller, so they likely require a button press from a player to determine which controller that player is using. This way, no matter which controller each player is using, after the game loads you can determine who to consider 'Player One' by asking them to press a button.

PC does not need to do this because there is only one player and one controller: the mouse/keyboard.

Edit: This was a guess, but there are actual game certification reasons for having the extra button press. Please read the other provided answers.

This is likely to determine which controller is being used by the lead player, as the controller in the first console slot is not necessarily the one they are using. Once they press enter the game would register them as Player One, or whatever equivalent. PC does not need to do this because there aren't multiple controllers (one keyboard and/or one mouse).

Consoles typically have more than one controller, so they likely require a button press from a player to determine which controller that player is using. This way, no matter which controller each player is using, after the game loads you can determine who to consider 'Player One' by asking them to press a button. 

PC does not need to do this because there is only one player and one controller: the mouse/keyboard.