Once this game launches, most everyone needs to know how to play. An offline tutorial will:
1) Prevent server overload
2) Allow players to learn controls and functions before they get into a server
3) Give players a chance to test the game on their system and tweak graphics settings before entering a server
4) Get all the non-RP elements out of the way so that the player can RP from the start
The tutorial would include basic things like character control, interacting with objects and interaction wheels, and driving a vehicle. Buying items in a store and going to the movie theatre can be learned in-game.