You said that the kernel version is 7.0 but that it reports 6.1 for compatibility purposes. I said that they made it version 6.1 for compatibility purposes and therefore it reports version 6.1
Forget compatibility, Windows version numbering is pure marketing.
Actually, forget Windows as well. It was the Microsoft's attempt to copy classic Macintosh System during 1985 to about 2000. It failed. Yes, they managed to support i386 in 1990, which was huge at that time, but under the hood things did not improve much ever since. The huge hype about Windows 95 was all about new interface and nothing substantial that would have made things better. Last of MS Windows family was the huge failure of Windows ME, which was essentially Windows 3.1 with "new" '95 interface and lots of new bugs.
What we consider "Windows" today is in fact not an MS product at all. It was originally a joint development by IBM/Digital/VAX and MS only marketed/sold the product. I'm talking about "Windows NT" which means New Technology. It was done in 1993 (NT3.1) - 1994 (NT3.5) - 1995 (NT3.51) - 1996 (NT4) and back then (NT4SP3) it was a very good, high-performance and multi-platform product !!! Sadly, soon after that MS axed the original dev team and begun developing it by themselves [which was a huge mistake]. They failed to deliver NT5 because of that, but in 2000 they had to get something out so they released NT5 as Windows 2000 that was far from finished product. It is safe to say that Windows XP (released in 2001) should have been called "NT5 done right" (except the horrible interface but we're talking internals here).
So... I'm getting to my point soon.
MS indeed counts NT kernel major versions which are different than their marketing names:
Kernel 1 = NT 3.1
Kernel 2 = NT 3.5 and NT 3.51
Kernel 3 = NT 4.0 (basically NT3.51 plus W95 interface)
Kernel 4 = Windows 2000 (NT 5 beta)
Kernel 5 = Windows XP (NT 5 done right)
Kernel 6 = Windows Vista (NT 6 beta)
Kernel 7 = Windows 7 (NT 6 done right)
It is marketing names that makes it all confusing. First of all, they should not have called first NT kernel a "NT 3.1" just because that was their current Windows version. They should've just called it a "NT 1" to make things simple. MS has been a victim of their own marketing names ever since. Luckily, with Windows 7 they have finally got their marketing version numbers on par with their kernel.
For what it's worth, I consider this the Worthy Windows honor roll:
1993: Windows NT 3.1
1996: Windows NT 4.0
2001: Windows XP
2009: Windows 7
Gap between worthy releases: 3 years, 5 years, 8 years ... given this pace MS releases next worthy release in 2021 ;D