It is confusing, because Microsoft rather abruptly changed its mind about libraries.
Microsoft heavily promoted libraries as an innovative feature when they were introduced with Windows 7. By Windows 8.1, Microsoft was instead promoting SkyDrive (as it was then called) as the place to store personal files. Previously, SkyDrive was just another storage location that could be included in a library, but now it was superseding libraries altogether. A default install of Windows 8.1 omitted libraries from Windows Explorer (whose name was changed to File Explorer in Windows 10) and you had to edit the registry to make them appear again.
Today, Microsoft wants everyone to store all their personal drives in OneDrive (which is the replacement name for SkyDrive) and libraries are but a memory. Libraries still exist in Windows 10, but only to maintain backwards compatibility with applications that are hard-coded to save files to libraries.
You can draw what lessons you like from this, but here is what I decided: When Microsoft puts their own spin on a commonly used technology, I'm going to stick with the commonly used technology.
I never used libraries, sticking instead with the same folder system that everyone else uses. I also never used Homegroups, WiFi Protected Setup (WPS,) or the XPS format for documents, all of which are either dead and gone or all but.