OSNews

Sure, this happens, but not after 18 months.

You left out that every successive release of OS X is getting spaced farther than the last. They're fueling a massive buildup of OS technology in a short amount of time, and they need renewable consumers to do that. It's not like Microsoft's infinite budget and refusal to engineer anything truly new. They're in the fastest stages of growth, but slowing down all the time.

Also, almost all the software I see says it will run on the current and previous minor version of OS X. You only need to upgrade every time if you just gotta have Apple's new bells and whistles. If all you need is free software from the Internet, you can skip every other release. And if you're using professional stuff, it's not going to require Apple's toolkits to do its job, so anything should work, but newer will be generally faster and more reliable.

Any company will want to give you a reason to upgrade, but in Microsoft's case, the reasons seem to be a lot more fundamental, like security and basic function (does it boot? Will it still boot tomorrow?), rather than superficial, like a really neat search tool. Look at all the comments on that article from a while ago about security holes in 98 that weren't going to be fixed. People still using that were pretty much called the scum of the Earth, complete morons deserving of whatever horrendous virus they get. You don't see that so much with other systems. You could easily get away with using Solaris 8, Mac OS 7, Linux 2.2, or any version of BeOS without anyone wishing righteous doom on your computer.