I noticed Apple’s software quality decline the moment they committed to 1-year release cycles. Because an x.0 release inevitably has issues, it offers less than a year of stability (sometimes only a few months if it takes until x.4 to be fully stable) before things get broken again in y.0. And because Apple stops signing old versions pretty quickly, you’re often stuck on an unstable new version if you take the risk and upgrade.

Additionally, it is hard on all developers (Apple included) to release updates for all of its many platforms on the same day, which IMO reduces software quality across the ecosystem.

(Apple also has the luxury of only supporting the latest OS versions with its software. Customers often expect third-party developers to support a wider range of OS versions and devices than Apple does.)