Except MS has unified their ecosystem so this MS account you keep spouting is actually tied to your Xbox account, your Win 10 account and everything else associated with MS and their users. (n4g.com)
The «World» in the title references to the new unified ecosystem in the game, in which players will navigate seamlessly from one area to the other, with all the elements in the environment such as enemies, objects, or traps, affecting each other. (attackofthefanboy.com)
Soon, Apple's certification process and APIs mean that HomeKit enabled devices will form a single unified ecosystem across the entire Home app. (techradar.com)