Seems odd that Kaby would only work with 10; i suppose it might be a driver issue. Hum.
It has to do with chipset support. Intel has stated they won't support older versions of Windows. While it supports Microsoft's interests moving forward, it also makes some sense for chipset makers... who wants to add to their support costs?
That said, there's nothing wrong with Windows 10, unless you have some terrible legacy hardware or software to support that won't work in a modern OS. The spyware is just as bad in Windows 7 and 8.x after Microsoft's "updates" - but the reality is that most of the supposed "spyware" is legitimate telemetry for support purposes, rather than something more nefarious, and 99% of marketing data is just used to direct more useful ads at users (which is in your interests as much as the advertisers - if you don't want any ads, block them, otherwise, be thankful you aren't assaulted with mistargeted ads for depends and vegamite).