This is an entirely separate question. For the most part, we need something as an octane booster. Ethanol performs that function. Tetra-ethyl lead and MTBE have been used in the past, but rejected for various reasons. Gasoline has been a blend of chemicals, not just straight petroleum distillate, for far longer than either of us has been alive.
Ethanol seems to have gotten a boost when it was found that MTBE, from gasoline leaked into the soil, was not being eaten by the bacteria.