Clearly wrong, Mac OS has been at 10 for almost 25 years.
They don’t call it OSX anymore. They renamed to macOS in 2016. Then in 2020 they changed the naming scheme from 10.X to X. There was 10.14, 10.15 and then macOS 11, macOS 12, etc.
Windows has been at 10 for a while too.
Windows 11 runs on the Windows NT version 10.
I don’t think NT version means anything anymore, except for some compatibility checking, but I think modern software checks more for dependencies than what Windows version it is running on. The reason probably is that not much software uses native Win32 API’s anyway but they use frameworks, libraries, etc., and these probably check for something else than NT number (like feature update string or OS build).
I can be wrong though.
We peaked with Windows 2000. Operational systems have been going downhill ever since.

