Sending Input to the Game Server
Pros
- The computation for all players is done at once on one machine.
- Each player receives the same game state.
Cons
- The player has to wait for the server's response to his/her input.
Sending Game Actions to the Game Server
Pros
- The player will not experience any latency relating to his/her own actions.
Cons
- The server has to stitch together and arrange multiple events from multiple players to be sent back out to the players.
Summary
It takes more work for a server to listen to multiple player'splayers' actions than it is to just take their input, calculate the result, and return a game state for all players.