This is All Very Well, But....
I learned to fold fitted sheets several eons ago. My issue with fitted sheets is a bit different:
They don't fit any more. Mattresses are all sorts of different thicknesses nowadays, and sheet makers make all sorts of different skirt depths to fit them, and there is evidently no standardized system to point out what fits what. Even worse, mass-market retailers sell sheets with an "average" skirt depth (the part that goes down the side of the mattress and tucks under it), which means they sorta fit everything, but not really.
Back when dinosaurs roamed the Earth, mattresses were all pretty much the same depth, and contour sheets were all capable of fitting them. Now, nothing really fits anything.
This is progress?