Just a note: this isn't really true. RAII was initially used to deal with exceptions. If you want fast backtracking and just reset the stack pointer (rather than unwinding) then stack-allocated RAII objects won't work since they will be overwritten. You need to maintain a list of "destructors" in thread local memory or close to the stack root so that you can close files etc. Whether RAII is the best option really depends on what kind of execution patterns and performance characteristics you are aiming for.
Why would you reset the stack pointer? Keep in mind, nobody uses exceptions in games. No exceptions are going to be thrown in a game context.
