No, they are perfectly usable and functional even on Windows XP or Vista or 7 computers that haven't been touched or connected to the internet since 2012.
It's backward compatibility if Word 2003 runs on the later Windows versions - like Windows 10 and 11. I don't know the answer to that, but I'm sure someone here does.
Though it's possible to mix and match so the OS backwards compatibility isn't the full story.
i.e. a launch copy of Word 2003 works on later OS updates, yet the final patch version of Word 2003 also works on a 2009 launch copy of 7.