Player datablocks are trackable on a GUI, but it'd have to refresh continuously to show them moving accurately. This process causes a lot of lag.
You can't track the datablock. Datablocks aren't physical objects, they are information objects that tell the client and server how this object looks and what it does. But yes, you can track players, but only if the server is constantly telling the client where the players is, and this would cause aimbots to work.
