That means that many Windows, Windows Phone, Outlook.com/OneDrive, Office 365, and Outlook/Office users can no longer sync or share contacts, calendars and other information with Facebook, the world's most popular social networking service.

Most alarming? There's no fix. And no fix is coming.

Microsoft started down this integration path with the release of Windows Phone in 2010, and since then, it has added similar services integration functionality to Windows 8 and newer, Outlook (part of Office), Outlook.com and OneDrive, and other relevant platforms. The idea was to let users consolidate all of their information in single end points, so they wouldn't need to launch different mobile apps to perform different tasks.

This integration was good for users, but it was bad for brands, and Microsoft started stepping back from its integration plans in more recent versions of Windows Phone and Windows, in particular, so that users coming from Android or iOS would experience something more familiar.