No, not true. Just had an extended argument with a friend over this. Here are some of my arguments against what you're saying:
1. While it's true that a human player could see everything the AI is seeing, the human player has to spend time and clicks to go see those things, whereas the AI sees it all simultaneously without having to use any actions or spend any time to take it in.
2. Emphasis on the computer seeing it all simultaneously. The computer can see the state of two health bars on opposite sides of the map at the same time, or 100 healthbars in a hundred places at a time. A human cannot do that, and even trying to move the view around fast enough to do so would render it impossible to actually do anything else.
3. If it's true that seeing more at once is not advantageous, then it must also be true that seeing less at once is not disadvantageous. So by that reasoning a player playing on a 1 inch x 1 inch screen would not have any disadvantage, since after all they're getting just the same amount of information as long as they move the screen around enough! Reducto ad absurdum, a player with a 1 pixel x 1 pixel screen has no disadvantage either, because they have access to the same information as long as they move around quick enough. It quickly becomes evident that smaller screens inhibit your knowledge of the game state, and therefore larger screen benefit your knowledge of the game state.