That's correct. 98 was the first release to have it, chronologically speaking. 2000 was the first NT based Windows to have it.
So 98/NT didn't make sense to me. NT4, the last release to use the name NT, had a very Win95-like appearance. I also remember NT 3.51 (and I guess there were other 3.x) that had a very Win3.1-like UI despite being 32 bit.
Of course but the problem with updates is that you can never only get security updates... You have to get "feature enhencements" too... It would be nice to have 2 branches.
Even more to the point, the kernel major version number represented an implicit ABI compatibility for drivers.
Windows 4.9 could load drivers for 4.0. 5.2 could load drivers for 5.0. 6.3 could load drivers for 6.0...
Windows 10... can still load 6.x drivers, but it bumped the internal version number to 10.0. It is worked around because without an explicit "I'm Windows 10-compatible!" manifest, the OS just lies and reports an internal version of 6.3, along with the ProductName string remaining "Windows 8.1"
Makes sense, but they also had pretty aggressive detection of when compatibility mode would be helpful, so solving for the bugs with that seems like it could've worked. But I always like a good major version skip, e.g. Winamp (no 4, because they combined 2 and 3 to make 5), PHP (no 6, because... reasons), and nobody so much as thinks about IPv5.