My guess is it was stored with ethanol fuel.
I drain everything and refill with premium/ stabilizer in the off season from chain saws to lawn mowers, weed whackers, power washers, snow blowers, snowmobiles, generators, etc. I run a small business that uses a lot of small engines. I've never had a problem pulling something out of storage and firing it up.
Plus I don't the have time to overhaul carburetors and drain out rancid fuel before I sent out a piece of equipment to a jobsite.