I bet 35 years ago they didn't sit as long either.
25 years ago when i moved to kansas, i left my 75 CB750F and 74 RD350 at my dads. He's not a motorcycle guy, at all, but he was willing to start them once a month for me. 2 yrs 3 mos went by before i got back home and they were both just fine carb wise. Maybe ive just been lucky for the past 30 years and.. 80? or so bikes.
also, fwiw, as far as stabil, sea foam and such... sea foam is for 2-stroke outboards. stabil was intended for leaded fuel, and startron was lauded as being 'the cure' for ducati fuel tanks made by acerbis that had swelling issues. All i can say is, ducati warrantied my tank on the sport classic evn though i used the startron, and i can tell you my ex father in law who believed in stabil used to get me to clean his hateful carb on his VTX1100 every year after he 'ran it dry' with stabil and left it for 4 mos. for years, every year. FI bikes do not suffer the same fates., the '14 gladius i had sat for 2 years in a police impound yard. I got it home, stuffed a battery in it and it ran just fine on the swill in the tank.
that being said, most of it is flat out snake oil.