"Is that really cheating?"
Not if you think it's O.K. to have an open book next to you during a semester final...so you can look up the answers. Or, in the case of a chess tournament, have a computer loaded with Chessbase next to you (why bother walking all the way back to your room or car?)
The point of the game is to match your wits (or abilities that come strictly from your head/memory) against those of your opponent. Best analogy I can think of is putting tracing paper over a famous painting, then claiming the resulting painting as your own...rather than painting just using your own abilities and what you've learned from teachers and practice.
Makes sense I quess. But what about football coaches looking at their scouting reports or photos of the other team's alignments during a game? Wouldn't that be similar?