Apple has a pretty vicious hardware/software upgrade treadmill.
I resisted updating 10.4 for years; IMO that was the high water mark for OS X, everything has basically been downhill from there. If I could still run 10.4 plus bugfixes and security updates, with modern software, I would.
But that's not possible. They push out new versions of the OS, along with new versions of development tools, which produce software that's not backwards-compatible past a certain point, such that eventually you can't run new software without installing major (0.1) updates. Apple's own products are the worst for this, but eventually you lose 3rd party apps as well.
Even if you resist the demands of new software, you'll eventually get forced to upgrade via hardware. Each generation of Apple hardware has a minimum OS version, keeping you from going back too far. For instance, Mac Pro "quad core" and 8-core systems won't run OS 10.4; Nehalem-based machines won't run 10.6. And Apple has purposely killed off its compatibility layers, dropping first the Classic environment and more recently Rosetta, in order to introduce barriers to running old software.
Classic/Rosetta were dropped during the moves to x86 and 64-bit. Given that almost all software was upgraded I can see why Apple didn't think the effort was worth it. And for all we know it could've been technically impossible.
I resisted updating 10.4 for years; IMO that was the high water mark for OS X, everything has basically been downhill from there. If I could still run 10.4 plus bugfixes and security updates, with modern software, I would.
But that's not possible. They push out new versions of the OS, along with new versions of development tools, which produce software that's not backwards-compatible past a certain point, such that eventually you can't run new software without installing major (0.1) updates. Apple's own products are the worst for this, but eventually you lose 3rd party apps as well.
Even if you resist the demands of new software, you'll eventually get forced to upgrade via hardware. Each generation of Apple hardware has a minimum OS version, keeping you from going back too far. For instance, Mac Pro "quad core" and 8-core systems won't run OS 10.4; Nehalem-based machines won't run 10.6. And Apple has purposely killed off its compatibility layers, dropping first the Classic environment and more recently Rosetta, in order to introduce barriers to running old software.
It's pretty frustrating as a user.