Tangentially related — in 2006 I got the first edition of the Mac Pro. It's probably the very best computer I've ever owned. It's no longer my primary machine at home, but I moved it into my lab for my students to use. When they find out they're using a 9 year old machine, they're blown away. In this case, Apple in its capriciousness decided that Lion was the end of the line for those machines, and put roadblocks in the way to prevent them from booting up in any subsequent version of OS X. Long story short, these "64-bit machines" (as they were sold to us) don't run in 64 bits while during the boot-up process, and Apple has declined to provide a 32-bit compatible EFI file from Mountain Lion on. After letting the (real) geniuses on this board and elsewhere do their thing and come up with the protocols, I've had every version of OS X installed up through Yosemite on that machine, and it's been at 100% runtime, year after year after year. (The only real issue seems to be that base model 2006 Mac Pros had a graphics card that isn't supported in later versions of OS X — but if you didn't replace that dog of a card, you're probably also not in the population too concerned about running an up-to-date OS).
So anyway, point is, Apple makes decisions about these things that do not always appear to be with the user in mind.
edited to clean up some typos caused by my furious rage.
I know, I have an old 2006 MP at work that has been purposefully obsoleted. And it has an upgraded 8800GT card in it so it could very well run the latest OS.
What did I do with it? I put a SSD in it, and it's running Windows 7 as a PC. I even tested Windows 10 on it, and it runs it just fine, in 64bit no less.