There was a bunch of Source-engine stuff Valve published, which is usually my go-to citation when arguing with players who don't understand "netcode" for a game but criticize it for not giving them perfect instantaneous communication anyway. :p
https://developer.valvesoftware.com/wiki/Latency_Compensatin...
https://developer.valvesoftware.com/wiki/Source_Multiplayer_...
Also there is this pretty interesting talk from bungie back when they did halo games: http://www.gdcvault.com/play/1014345/I-Shot-You-First-Networ...
Think of two players running towards each other, and shooting at each other. By the time the player (or even the server) receives the data saying the other player has fired their gun, they've both moved to completely different positions.
(There is a good set of articles on this by a game developer, I can't find them now)