Not much technically, they do it artificially (purposelly), it could all be supported, only with some specific new features not available.
+1 agreed in full.
"What exactly is preventing new hardware from running Win7 ?"
Nothing. Zip, zilch, nada, rien. MS does it to keep you riding their "train", as I see it.
By comparison, I know from experience ( because I use it occasionally ) that Linux Mint supports
everything, or at least tries to. Why? Because its written by people who want it to
work on everything, IMO. The main problem with Linux ( and anything outside the Windows OS platform ), is
software support. A little history as I understand it ( for those who were not "there"...I learned this in college during the '90's from my then-60+ year old instructor who worked for companies like Hewlett Packard and Motorola ):
1) During the early '80's, IBM built the IBM PC in response to Apple's business inroads.
2) MS partnered with IBM to license DOS on every machine they sold.
3) IBM's PC used mostly off-the-shelf components to build it, AND they published some, most or all of the schematics for it in the first few issues of PC Magazine ( unconfirmed ).
4) " Taiwan Joe" ( that was my instructor's nickname for the electronics manufacturing sector in Taiwan ( Formosa )) got hold of the schematics and mass produced the "IBM compatible", and everyone jumped on board...making Microsoft millions by the end of the decade.
5) Competition was fierce, especially in the late 80's and early 90's, between all the IBM compatible makers starting up...Magnavox, Compaq, Dell, Gateway, Tandy ( Radio Shack ) and countless local shops all getting their components from the same group of manufacturers.
6) During the 90's, the home PC market literally exploded...but there was only one established and reliable source for operating systems:
Microsoft. Oh, there were others...Digital Research hung in there as best they could, and Apple always made money from their machines. But there were few others who tried and succeeded. This made Microsoft even more money, because the vast number of "IBM Clones" all needed ( or worked best with ) their OS. They stayed on top of things, and I admire them for cornering the market. To me, they established a standard when one was really needed.
7) Up until 1995, Windows was always a "shell" that loaded on top of DOS in memory as a user interface ( I think they got their idea from Apple, because I remember seeing "windows" on the Macintosh Plus in 1988-ish ). After Win95, it became a full-fledged operating system...sort of.
I won't get into it, because I'm not sure if I know all the relevant facts.
8) Now we find ourselves where we are after almost 3 decades of Windows dominance ( and well
over 3 decades if you include MS-DOS ), and nobody has come along to seriously challenge it in look and "feel" except Linux Mint ( at least in my mind ) and Apple's OS variations. If there is anything else outside of the Unix-based Linux kernel and Apple's OSX and variants in the consumer market, I'm not really aware of them.
So, after that long-winded bit of nostalgia and partial editorial ( whew! ), I'm not surprised that it has taken this long for Win 10 ( which was released to much fanfare by MS, and little to no real enthusiasm on the part of mainstream PC users...especially enthusiasts and power users, my impression of it at least ) has finally garnered enough user base to bump up to it's place among the OS's.
Why am I not surprised?
Because like any of Microsoft's previous OS's, they gradually phased out the older ones and very nearly forced new computer buyers to adopt their newer edition(s) of their OS; and Win 10 is just the latest in a long line that started with Win95, IMO.
Addendum:
Here's the real problem
from my point of view:
Unlike older OS's, Win 8 was even
less popular than Xp on release...umm, maybe, and we're not talking about Vista
. Because of this, MS then backpedaled and introduced 8.1 to smooth over the upset customer base, all the while developing Win 10 as a compromise between 7 and 8. Next, in order to keep the daisy chain going, they very nearly forced their next OS upon millions of computers to overcome the built-in resistance of people who inherently want to keep that which they are used to, or like and don't want to change, and almost succeeded in soft-hijacking the lot of us.
What they don't want is for people to settle in for a long winter's nap of game playing and software use, only to stop buying OS's every 3 years or so. <---- Again, opinion, but I think I have historical weight on my side with my observations.
There it is. My "two cents" and my impressions of Microsoft's business model for the past 3.5 decades. Dear reader, there's a reason MS went from a small suite ( or was it a garage...no, that was Apple ) in the early 80's to a campus with satellite locations today...it's called
marketplace dominance, and buying / forcing out your competition along the way. It also doesn't hurt to establish ones' self as THE defacto standard in all things home PC.
Ya gotta love capitalism!