Re: I can sort of understand it
"I can too, to some extent, but why does Linux run on more or less anything without this "legally required to support older hardware ..."
Of course, if Apple made it a priority, I'm sure they could support just as much hardware as Linux. But they don't. Technically speaking, no sane person can argue that it's easier to support more hardware. More testing is required, existing code is more complicated and thus harder to maintain and improve, new code is harder to write, etc. So while somebody might not _like_ that Apple drops support for hardware at a relatively quick pace, it's hard to argue that there's no technical justification for doing so.
At one point I was pretty annoyed that support was dropped for a particular model of MacBook but not a Mac Mini with exactly the same processor that was actually _older_. But then I found out that the MacBook had a different/older UEFI version with different capabilities and reasoned that they no longer wanted to spend their time supporting that firmware and it had nothing to do with the processor/chipset. So while it might sometimes seem arbitrary, I have yet to see a case of Apple dropping support for something with literally no technical justification.
"Don't you think it's more about a demand to sell new hardware than adding some "if,then,else". Please don't fool yourself."
I'm sure Apple is _aware_ that they are likely to sell more new hardware if they drop support for something but, as mentioned above, I'm confident that when they drop support for something, there's a technical reason, and not just a business justification. That's why you see so many irate posts to the tune of "hey, my hardware is 2 years newer than this other supported hardware, why can't I use the new OS?" etc.