So if the only way to install a Windows Store app on Windows 8 without the Windows Store is to sideload, and in order to sideload you have to enable sideloading on your device, the obvious question is, can everyone enable sideloading on their devices for all Windows Store apps without Microsoft's permission, thus making the platform effectively open. You can enable sideloading on Windows 8 Enterprise or Windows Server 2012 by joining the computer to a domain.
To enable sideloading on a Windows 8 Enterprise computer that is not domain-joined or on any Windows 8 Pro computer, you must use a sideloading product activation key. To enable sideloading on a Windows RT device, you must use a sideolading[sic] product activiation key. Here, Microsoft has listed two different sideloading methods: one that requires domain joining, and one that requires a product key.
Insofar as it is discussed in Microsoft's current publications, the domain-joining method is actually much more like traditional open distribution.
The reason. They wanted to use the program's status message, which allowed them to type a short note telling their online buddies what they were doing, even when they weren't at the computer. Messages like "gone shopping" and "studying for my exams" became commonplace.