You need to take better care of your stuff!
All of my gear is way over 20 years old. I have never had to replace as much as a piston, valve or even head gasket. Once in a while I had to dump out the carburetor bowl, until I learned to run them out of fuel. Now...no problem. I have snow blowers, lawn mowers and tractors that old.
The main things I have to replace are belts and bushings in the drive mechanisms. All of them have been converted to electronic ignition.
I change my oil whenever it looks dirty.
Ethanol is highly corrosive to aluminum
You want to explain that, like in a chemistry context. Acid is corrosive, water might be. Tell us why alcohol is so damn corrosive.
it degrades rubber seals and vacuum lines
They haven't used rubber in decades.
and opens up the sand pours of cast block engines - thus causing increased oil consumption ... those are not suppositions, but proven facts.
I'd like to believe you but.....
People up here don't have a lot of money, they run their cars till they fall apart from rust (road salt) When the engines fail, it's generally from lack of maintenance (oil changes)....not the issues you allege. Usually they brag of 2 to 300 thousand miles...REGARDLESS OF BRAND NAME.
Fuel systems in these small engines use a lot of manmade materials, like tubing and yes, gaskets, filters, and even the carburetor floats.
All of these things are subject to degradation in the presence of alchohol. It makes them stiff as a board, and without the flexibility the vibrations take their toll, causing fuel leaks, blockages, stuck floats, and the debris fouls the rest of it.
It has nothing to do with pistons or head gaskets..