I also wonder why anyone would do this. I have used E10 in riding lawn mowers, small engines, portable generators, etc for years. Some of them will sit for some time between uses. I have never had any issues. I do add PRI-G stabilizer to the gas that goes into these. This phase separation thing and other ideas, usually promoted by those that have some sort of ethanol phobia, I have never concerned myself with.... in almost 4 decades of ethanal blend gas use.
But to each his own. I never chide anyone for being cautious if their gut tells them to. I just never wasted any time worrying about such things.
In order to know what is bad, you have to know what is good. The question them becomes, what is the source of knowing what is good?