Nothing has created more confusion in the world of photograph than "crop factor" (no, not even the zone system.) I used to frequent a mostly digital forum and almost every day I'd see one or the other strange misreading of what it was and how it worked. One person was asking some questions about using an 25mm APS-C lens on a Micro 4/3 camera and was convinced that he needed to do two calculations--APS-C to FF, then FF to M4/3 because a APS-C 25mm was different than a FF 25mm--so (25*1.5)/2. People on the forum tried to patiently explain that 25mm was an unalterably real world physical value that was independent of sensor size, but he kept arguing and arguing until I decided never to click on that thread again.
Today I just tell people to look in the viewfinder to figure it out, and learn that each sensor/film size has its own view of a focal length.