What do the map hacks accomplish? Can you see full unit information across the map? I doubt this is the case, except for the game host. For clients, I'd be surprised/disappointed if this were true as it is not costly to filter the information from clients if FoW visibility has already been calculated.
My guess is that the main technical problem preventing this in SC2 is related to the game's replay-saving system. If you have only partial data, your client can't include the data from the opponent's perspective, which makes the replays suck. Theoretically you could generate the replay server-side but it would be resource-intensive without a costly technical overhaul.
Yeah, I'm surprised they didn't design for this. Typically replays (in any game) are a log of initial state and then player input commands, rather than complicated state streams. Input commands are simply replayed in the simulation. It seems possible to keep the master log of input commands and then simply replay the simulation on a client during replay. With this design you could filter inappropriate information from each client during gameplay but have full replay information.
I'm sure there are good reasons why the design in SC2 is as it is, but this was surprising! Thanks for the info.
> Can you see full unit information across the map?
Yes. The engine works by syncing the entire game state between all players (and observers, which in tournaments can become an annoying issue) and all clients have the same information.