I was a software developer, and have some idea where this comes from. Keeping track of multiple versions of software to separate bug fixes from new features is hard, but calling whatever is in version control on the first Friday of every month "version N+1" is easy. Back when users had to pay for a stack of floppies or CDs to get a new version, you had to give them a compelling reason to do so. When it's nearly impossible for them to prevent the new version from being auto-installed, you don't.