Agree, but there is an advantage to running E85. It burns super clean. So carbon buildup is not an issue. Another one is the higher octane, and one other thing, at least for me. I like the smell of the exhaust.
Yes, you get lower mpg that is a given. But depending on where you live and are lucky to have a ton of stations around with it. The cost can be worth the lesser mpg's if you calculate cost per mile. Like here the cost of E85 is a dollar less a gallon than 93, which I run since I'm tuned for it. So running E85 works out to be less expensive even though I'm filling up more often.