Bologna. Windows 8 was launched over 3 years after Windows7. Windows7 came out about 2.5 years after Windows Vista and Vista came out over 6 years after Windows XP. I don't see even a single example of a ONE year update interval.
As for why, I would say Snow Leopard wasn't even working right and/or stable compared to regular Leopard until at least 10.6.4 if not 10.6.6. I waited almost a year to update for that reason. I didn't update to Lion period it was so unstable and wiped out so much software (i.e. all Rosetta PPC emulation). I'm fine with Apple doing point updates, but they're basically turning point updates into major releases and then touting it's only $20 to upgrade when Windows doesn't charge anything for those updates so it's just a marketing gimmick. Worse yet, they're using it as an excuse lately to stop support for older machines each update (probably the real reason it's being accelerated so much).
http://www.tomshardware.com/news/Windows-8-Windows-Phone-8-Windows-Blue-Surface-Foxconn,19382.html