All true - which is why an ethanol treatment is absolutely required for small engines and if you expect to park a car for an extended period you should put treatment in the car’s gas tank as well.
E15 makes this worse than E10, but that’s all true for E10 as well. The problem isn’t E15 vs. E10, the problem is putting ethanol in our gas in the first place. The original reason was to reduce greenhouse emissions, or so it was claimed, but 50 years later it’s STILL not possible to produce an energy equivalent amount of ethanol that results in less total greenhouse emission than just burning fossil fuels. And that’s never going to change. We’re putting MORE greenhouse emissions in the air using ethanol.
Bickering over how much ethanol is in gas is sidestepping the issue. We need to stop subsidizing corn for ethanol.
You suggest “treatment “ but treatment does not kill the corrosive effects. I never use ethanol in small engines.
My beater car is a 2012 Chevy Sonic with the 1.4 litre turbo. It has 208k and still gets 38 - 42 mpg. Its exhaust is very clean, and most younger vehicles burn even cleaner today. Given the amount of oil being produced thanks to more drilling and fracking we just don’t need ethanol. I say use the corn to make booze (kidding). Seriously I think the farmland could be put to better use.