Do you remember when there used to be entire sections of bookstores dedicated to books like "Learn to use Word 98"? These books were always incredibly thick, so one time I opened one to find out how there could be so much to write about Word 98 (or whatever it was). Turns out it wasn't written so much as screenshoted. And I realized this made perfect sense - a non-technical audience needs to be hand-held through every step, and a GUI application is inherently visual not textual, so a text-based guide would just be harder to follow.