Wouldn't this feature allow for one team who has an active spectator watching the game without fog of war to give advices of incoming ganks, jungle invades, Baron, Dragon kills etc.?
The source of why I know theres a Fog of war feature is here Next Patch: The Full Release of Spectator Mode!
Best Answer
There's a 3 minute delay in spectator mode, so the only cheats that people have cautioned about so far would be watching a ward get dropped.
Since a ward is alive for 3 minutes long, a spectator could communicate that to someone on a team, and the team would instantly know that the ward there was now gone.