The tape cutter is !! not !! there to cut tape from the tape roll !!!
A tape cutter is used to remove the tape bandage from the joint or muscle. For the thin tip of the cutter is placed under the edge of the tape dressing and then pushed through the dressing. The blade cuts the tape like butter.
By the way: The Tape Cutter MUELLER is pretty much the best selling cutter and thousands of times in use, similar products are available en masse.