Sorry. Factually wrong.
I just had to reformat my machine a couple weeks ago and, just like the first time I set up the machine from the Windows 8 final retail version, I used a Local account (no Microsoft Account tie in at all). After I installed all the normal Windows 8.0 patches I clicked the store and right there on the left was the huge-ass tile for the 8.1 update. I clicked it the machine started downloading it, and I went out for a couple hours to run some errands. No login prompt at all.
When I got home it was (coincidentally) just finishing the install.
I have a Hotmail account but I never enter the information on Windows 8 Mail (because I've heard it will convert a local user account setup to a Microsoft Account enabled one if you do. I also never use Skype out of the same concern. I access the Hotmail account as IMAP in Thunderbird, same way I do all my other email accounts, and IM with people on the MSN Messenger network using Pidgin to connect to it (news of MSN's death are greatly exaggerated -- by Microsoft to get people to start using Skype).