I played goalie my entire life and I think there are arguments for both sides of the above argument.
In addition to knowing your player's tendencies (which isn't a system, you can't teach that, it's learned from being on the ice every day.) Different coaches, teams, systems tend to have a few things that the goalie will communicate with defensemen. An example is the during rushes, depending on whether its an odd man rush, even or 1v2, 2v3 etc the goalie will communicate that situation to the defensemen. Others are on breakouts, PK strategy and stretch opportunities. There are a few things that we can consider system based for the goalie.
On the other hand, the above things to learn are picked up quickly and quite frankly, the only thing that matters is that the goalie stops the ******* puck and throws the rest out of the window.