Once upon a time (mid 70's I seem to recall) Kodak actually sold a bulk load film with the narrowed leader, and a a notch of where to cut the film.
Edge numbering is just a convenient reference. Some Freestyle Arista films do not have them, and I do just fine. On a bunch of my cut down films I use for varied projects with obsolete film format cameras,I never expect edge markings.
All my films get into neg filing sheets, and in the case of no edge marking they get referred to as row x , frame y, where y is somewhere between 1 and 5 usually.