Anytime anything about chainsaws is posted you'll get a wide variety of responses going in all kinds of directions. Conditions will also vary widely. When someone posts, "Well, I've never had a problem" doing this or that, it may not really apply to each and everyone else, there is no "control" on this, meaning all do the same thing with the same saw the same way, with the same fuel, in the same wood, each and every time. Does not mean anyone or anything is wrong.
I'll now make one of those posts LOL. I have had little time to do the things I like, the job takes up much of my time and energy. My saw, (a stihl MS 390)sat at least a year, might be a year and a half in reality. I've been getting back to working on gathering logs and working on firewood and needed the saw, over a month ago. I know with small engines that sit, you'll have to get fuel up to the carb with a few extra pulls. This saw after about 6 pulls, fired on full choke, and stayed running until I moved the lever. Often they stall, you move the lever, pull again and it starts and runs.
I use ethanol free premium in everything, vehicle too, local convenience store offered it after customers requested it or something along those lines, throughout their regional chain. I'll pinch pennies somewhere else and I don't really live any kind of extravagant lifestyle anyways. I use stihl 2 cycle oil and nothing else. I was using startron with ethanol gas, with good results, not sure why, but had no fuel related problems.
I used to use gasoline with ethanol, lowest cost at the pump whatever it was and nothing to treat it and rarely had any fuel related problems in anything that sat, just by running whatever it was periodically, not allowing things to sit. I do believe the fuel line that failed in the MS 390, some 5 or 6 years back was related to ethanol fuel. It was cracked, leaking, but the saw would still run. I replaced that fuel line myself, took an hour. I took this saw completely apart aside from the engine a few years later, and had been using that ethanol free gas. I replaced all the hoses again, and the fuel line was just fine, as were other rubber components. Not sure if it made a difference or not, but it seems that non ethanol fuel and stihl 2 cycle oil is a good combination from this perspective, I'm not a chemist or petro-engineer. I have been using moto-mix in my KM 130R Kombi, I don't use it a heck of a lot, and there is no trouble getting it to fire when it sits a year. I like that fuel as the exhaust fumes are not so noxious or irritating. The moto-mix is not a bad option for filling a saw that will sit awhile. 1 gallon can goes quite a ways anyways. I used to think who would pay for that, but having used it on a limited basis, it seemed worth it. I mix my own for the saw as I use that more.