Problems with a computer, in other words, tend to mirror changes in the operating system, and conflicts between it, other targeted software programs and hardware. These programs have to work with the operating system in an intimate way, in effect modifying it, and could conflict with each other in various catastrophic ways. This set a new standard, but it conflicted with all the old ways of doing things. Suddenly thousands of Internet users who upgraded to Windows 95 had problems with their previous Internet hookups. This is why the computer-user pros tend to stay one revision behind the most current operating system, especially a system they count on to do useful work.
Newish hardware combined with older operating systems can have similar problems.
Computer manufacturers don't just sell the typical retail bundle of hardware and software for marketing reasons. Rather, there are sound technical considerations for having the operating system, hardware and software all matched and factory-tuned.