There is more than one reason why gasoline has ethanol in it these days. Yes, one of those reasons was a mandate from Congress that provided financial incentives to use it. But there are others.
Refineries used to use a product called MTBE (methyl tertiary-butyl ether) as an octane booster after tetraethyl lead was outlawed. MTBE also is an oxygenator, so it was used in the Reformulated gasoline required in many parts of the country to deal with air pollution noncompliance. Unfortunately, MTBE is a very hazardous and carcinogenic compound that was found to be leaching into groundwater thanks to leaking storage tanks or pipeline spills. It has been outlawed for use in gasoline in many states, so an alternative had to be found. One such alternative was alcohol. It has a high natural octane rating and is also an oxygenator. Many refineries were already using alcohol before Congress came up with their ill-conceived plan to subsidize taking corn from the mouths of hungry people and turning it into ethanol.
As for all the BS you will find all over the internet blasting ethanol in gasoline and blaming it for everything up to and including the failure of the Cubs to win a World Series, please don't be fooled by unscientific rants from people who don't have a clue about the subject. Yes, ethanol will slightly affect fuel mileage when blended at 10% or less, as is current custom for gasoline. But the difference is pretty small, not the big numbers thrown about by the folks who just like to rant. Now if you want to talk about E85, then yes the mileage difference is large and very significant.
Thanks to ozone levels that dump this part of Indiana into a nonattainment status with the EPA, I've been running reformulated gasoline for many years and since about 2005 if I remember correctly it has been laced with ethanol at up to 10%. In all the years since, I've had zero fuel system issues with my automobiles, my motorcycles, my yard equipment, etc. And some of those things don't get used on a daily basis and tend to sit with fuel in the tank. Somehow I haven't had a single one of those catastrophe's the anti-ethanol crowd likes to claim in their rants.

Jerry