No, this wasn't for Windows executables working or not working in a core binary technical compatibility sense. This was for where either an app or a website nee

No, this wasn't for Windows executables working or not working in a core binary technical compatibility sense. This was for where either an app or a website needed to test the version number against several possible versions of Windows to determine which version of Windows they were running on and react (or reject) according to the programming. For later versions of Windows, programmers applied other tests, but none of those tests stepped on the "does it start with 9" test for 95/98. Using 9 for the version after 8.1 would have done so.