I absolutely think that is just exactly what Apple wants. They want us all with older and perfectly working machines to throw them out and buy newer ones. Worldwide, that would be billions of megatons of $$$$$. Just what they want.
Such things is never an issue with a PC, because they last maximum 2-3 years anyway. But Macs last very much longer, and they have to come up with a solution to that problem. Either they can make Macs as bad as PCs or they can make incompatible software. I'm sure that's just what they have done. All this hardware requirements that don't make sense is just something they say to calm people down. But in the real world, they are greedy and want more $$$!
I have also noticed that the Safari is very, very unstable at the moment. It may be my very hard use. But it used to work just fine. I would not be surprised if they but bugs in Safari for machines that don't fit the requirements for OS Sierra, so that we have to buy new ones. Apple is an American company, and America is like the hotspot in the world for nasty companies and politicians, corruption and what not. So I would not be surprised. But maybe I use safari too hard with too many tabs at the same time. But everything crashes suddenly very often. Most likely it is just my machine, but who knows these days when people and companies are ready to kill just for some $, euro or norwegian crowns extra. (Yes, we in Norway sell weapons that is used to kill people in Yemen, for example).
Well, well, whatever the case is with this OS Sierra. I will never get rid of my old mac before Apple sends an electrical current thru my WiFi and blows the screen out and my hair off. Then I may think about it. I actually wanted this Sierra crap just to see if my Safari would stabilize. It might work just as well to install something older. Maverics or what the names of all the older ones were. They did work totally fine anyway.