I agree with waltero but maybe for different reasons.
If you tell your opponents your strategy or how to beat you they will do one of two things. Generally, if they are not a good player they will take you at your word. This makes them feel grateful to you and less like to attack you and get lucky. Also, genuinely helping a bad player play better makes them easier to predict and they will generally not become magically good enough to beat you. Generally, if they are a good player they will be confused by this tactic and spend trying to figure out if your trying to trick them or if your being honest and trying to trick them into thinking that they are being tricked and so on. Then, they will be stuck into following to paths one assuming you telling the truth and the other one assuming that you are trying to trick them. Either way they become predictable and sometime they will try to block both at once weakening them for either case.