Upvoted for some interesting points, but it's quite wrong for the simple reason that on a commercial timescale one year is nothing. There are reasons Microsoft end up being dragged into supporting old OS versions, and it's because running an operating system is just a means to an end, which hopefully is doing something useful. "Upgrades" have, understandably, become synonymous with unnecessary pain and breaking things.
Maybe OpenBSD really is more rigorous about quality control, but (as an example) if you were to just accept every Ubuntu update it wants to install you'd be wasting a significant amount of time just ensuring your system works properly.
I've worked in commercial environments where common invocations of `tar` did not work, because `tar` was a decade out of date. I had to learn things and habits that had died before I even started programming. It wasn't pleasant. Do not underestimate the age and stubbornness to upgrade of some environments.
Recently, I've helped migrate software from Ubuntu Precise to Trusty, and the amount of differences make things mildly frustrating. We don't get to just run one or the other, and we can't just drop everything and move to Trusty. We have to continue to support the old while we build support for the new, briefly support both, transition to the new, then tear out the support for the old. Migrated. It's a lot of work when the changes are huge, but much more manageable when I can take the changes more piecemeal (it's one if statement, as opposed to many, that I need to manage at any given time). That's in a production environment.
I run Gentoo at home. I much prefer its rolling releases to Ubuntu and Debian which I ran alongside and before, respectively. Things break every now and then. It's a tad annoying, but it gets fixed sooner or later.
This is implying that people actually want to upgrade full releases. Perhaps I would like to make a Linux box and have it last a few years, and only patch it for security fixes as it is working fine. Yes if I do have to upgrade that system 5 years later it is going to be more painful than every 6 months, but if I did it every 6 months I would have to devote development time and switch context every 6 months.
Small updates are better if you have to upgrade entire systems, but many people do not want to risk destabilizing working systems every 6 months. For that we have LTS where someone will integrate in security fixes in a hopefully non impacting fashion and for that I am thankful
Maybe OpenBSD really is more rigorous about quality control, but (as an example) if you were to just accept every Ubuntu update it wants to install you'd be wasting a significant amount of time just ensuring your system works properly.