I worked on a codebase that had this bug, so I’m not sure where you’re getting “this is false” from.
We sold software that was installed long-term at customer sites, and they weren’t going to update it until they needed to, so the bug persisted in production well after we fixed it.
Best I can tell it's only libraries that generate those sort of strings, which could just as well report a different string for Windows 9. The actual Windows API even returns the version information for Windows 8 if the application isn't manifested for 10 and onwards.
Company I joined in 2008 had sold software back in 2005 or so which had the bug, and customers were still running it in 2015 when Win10 came out.
The idea that "sensibly designed software wouldn't have this issue, so it must not exist" is absolutely at odds with virtually everything I've seen in my career.
We sold software that was installed long-term at customer sites, and they weren’t going to update it until they needed to, so the bug persisted in production well after we fixed it.