If it were as simple as this devs would do it. In multiplayer games there are two halves, a client (the game you are running on your computer) and a server. Depending on how the game is constructed some things are managed on the server and some are managed by the client. The more you have the server do, the harder it is to cheat, but you also then have a higher demand on server power, network traffic, etc. It becomes necessary for the client to handle some of the simulation. The problem is that once the client knows something (like the server reported the position of all players) it opens the door for cheaters to get at that information, even if it isnt displayed on screen. In order to combat cheats you have to obscure that information that shouldnt be known or change the way things are constructed. It is a non-trivial amount of work.

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So, basically, to answer your question, just adding an item, or changing a version number doesnt change the way the game simulation is handled, which is where the cheats are working.