I wonder if they're just counting on the fuel filter to catch the contaminants?
I believe their position is the tanks don't break down. I look at the contents of my fuel filters every year and never see anything but clean gasoline when I pour the fuel into a clean container.
I try to avoid e10 at all costs, but probably pick some up from time to time in Wisconsin. Still no issues. There are a lot of Tiaras running around the New York City area where e10 is the norm. Still no tank issues according the the company.
Getting back on topic, we do store full with Stabil and run that through all the systems (mains/genny). We will anchor out tomorrow and on the way home I will top off for the season. Boat will be lived on one final week end and then be serviced and stored. It will be 90%+ full of fuel---just enough to keep the tank from overflowing through the vents during the warm up in heated storage.