An autogiro derives its lifting force from its rotor, which is not powered by an engine but by the airstream flowing in at a positive Angle of Attack: from a relative flow that is directed upward through the rotor disk. So to an extent, the autorotating rotor provides the same function as the wing surface that was cut for mounting the rotors.
How best to compare whether the effect of the rotors is positive or negative? If we look at the L/D ratios of autogiro and fixed wing, we can identify the following:
Autogiro, from Leishman: a maximum L/D of 5 for the complete machine, and of 7 for the rotor only.
Cessna 172, from this link:: maximum L/D of 10.9 for the complete aeroplane, including fixed landing gear.
So fixed wing wins, hands down, by about a factor 2 - and that is for a large autogiro rotor which has much higher L/D than a small rotor. Plus, as @RonBeyer mentions in a comment, not cutting holes in the wing means that there is a convenient place to store fuel in.
Data and graphs from J. Gordon Leishman, Principles of Helicopter Aerodynamics, chapter 12.