The instructions for installing a library that a use downloads say to put it in the libraries directory of the sketch folder. An amazing number of people can not figure out that that means to create such a directory if it does not exist, or don't know how to do such a thing.
Now, it is no longer necessary for the user to create the directory. It will be created when the sketch folder is created.
While I agree in principle (PC users should understand and know when and how to create folders if required) but I feel the IDE installation should have always automatically created the user libraries folder if it didn't already exist in the users sketch folder when they first added the feature of user library searching for include files. It was silly of them to add that feature but not check and setup the user folder structure needed to support it.
I still remember the bad old days that every time one upgraded the IDE version you had to first save and then manual reinstall any 3rd party libraries one had added to the arduino core library folder, yech.