The tungsten "rippers" are indeed very hard on knives. As has been stated, they work reasonably well on very soft steel and aren't a terrible choice for "disposable knives." I suppose commercial fisherman who either don't buy their knives or buy very cheap ones have different expectations than your typical knife junkie. I've spent most of the last two decades cooking professionally and I've never seen a knife that was sharpened only on rippers that was in decent shape. Most of them look almost serrated.
My advice if you want a pull-thru is to get the Edgemaker Pro. It's a tungsten system but uses rods, more like steels than a ripper. It removes much less metal and will get almost any knife shaving sharp. The edge is more durable and long lasting, too. It's basically as fast and just as easy with the benefits of a sharper knife and much longer life.