Ethanol attracts water and it breaks down faster than gasoline.
With water absorbing into the fuel, there's the chance that rust will form on the interior of the engine. The particles that get into the gas from rust flakes will clog up the fuel filter sooner. It's possible that these particles can cause extra wear to the pistons, rings, seals, and any number of other components of the engine.
Ethanol increases gasoline vapor pressure which may cause a vapor lock in a carburetor. This fuel starvation will prevent the engine from starting. This is an issue in higher altitudes and hot weather.
Gasoline with ethanol decreases the life of the engine and its parts. The alcohol is not good for seals and causes a quicker break-down.
Having a cleaning agent like this constantly in a small engine that was not engineered for this fuel mixture simply ages it at a faster rate.