This is basically a follow-up to What's with the Windows-8 tag? because that didn't really seem to result in any long-term fixes to the problem.
The problem being that a lot of new users are tagging their questions with windows-8, even though the questions have nothing to do with the desktop OS. This creates a lot of overhead as the posts need to be edited to fix the tags.
I think the reason for this is two-fold:
New users don't know that we don't use "windows-phone" in tag names and that they should simply use the OS version number.
Many people don't fully realise Windows Phone is the actual name of the operating system. To them, "Windows Phone 8" is the same as "Windows 8 phone" (example).
As a result, they start typing in "windows", see windows-8 in the list, think "close enough" and click it. Yes, the tag wiki excerpt that's shown says it's for questions about connecting a Windows Phone device to a PC, but clearly people don't pay enough attention to that. After all, we still get questions mistagged with windows-mobile even though the excerpt explicitly says not to use it for questions about Windows Phone.
I think the problem warrants a revisit, and some more long-term measures to be taken. I'll post my suggestion as an answer.