Apple routinely holds back changes for a .0 release for advertising reasons. This means that they routinely have big releases that break everything at once. Bugs could come from 4 or 5 different sets of changes. But if they spread out changes… bug sources would be way more easy to identify.
And bug fix velocity going up could mean people stop treading water on bugs, and actually get to making changes to avoid entire classes of bugs!
Instead, people think the way to avoid bugs is to avoid updates, or do it all at once. This leads to iOS .0 releases being garbage, users of non-rolling release Linux distros to have bugs in their software that were fixed upstream years ago, and ultimately to make it harder to actually fix bugs.