The subject of this thread is ridiculous installation requirement, for the purpose of this discussion my emphasis is on installing Windows. I think MS would be better served if the extra step was after Windows is installed and on your first login to the MS account much like the Last test scenario (above Conclusion) in your post.
I'll take it one step further and suggest that a local account should take precedence at install time and prompt you for a MS account login after the install is completed, the machine is up and running and you can access the Internet in order to complete any steps MS deems necessary.
I think the issue is many-fold. Sure it's been around since Win8 and is documented many places, that doesn't mean it's a non-issue.