The popularity of Cutco knives is due to its appeal to common folks. As long as it can cut, grandpa and grandma can use them for a long time. The Double-D edge can cut, but in time it does get dull. Since you can't sharp it on your own, a lifetime warranty is a way to go. Our church bought a set of Cutco knives. In a few years they became dull, couldn't cut a tomato without tearing the skin.
This brings to another question on how to maintain the sharpness of the knife without sending it in. You can watch many Youtube videos on how to sharpen the knife. A wetstone could be ranged from $10 to hundred of dollars (the expensive ones are for sushi chefs). The cutting board is an important factor for the knives. A glass one will dull the knives quickly.
Here is the recommendation for various cutting boards:
https://www.cuttingboard.com/blog/wh...st-for-knives/