Scare tactics so you will buy the expensive rope markers.
I just use a large Sharpie. I mark a section of rope about 6" long all the way around the rope. If you don't mark a large section it becomes almost impossible to see after a dozen canyons. I've marked literally hundreds of canyon and climbing ropes this way and never seen an issue. My ropes usually have 3 marks which sections the rope into quarters.
Tap'n on my Galaxy G3