Things like a certain food or diet don't matter, it's things like drugs that *directly* affect your performance that matter. While I may improve my CC performance by practicing beforehand or playing when I'm in a good mood, I certainly don't use computers or memory hacks to alter the path of the blobs.
Studying chess based on certain openings is using the game itself to improve and play better, just like if one were to use certain techniques and maneuvers in sports that they learned and are perfectly within the rules, it isn't cheating.
Studying chess based on certain openings is using the game itself to improve and play better, just like if one were to use certain techniques and maneuvers in sports that they learned and are perfectly within the rules, it isn't cheating.