With some breeds you pull out the undercoat... Like with Schnauzers, they don't shed so a tool like this would help get those hairs out. It's mostly if you don't want to use a clippers on the coat. I used them when I showed one of my Standard Schnauzers... I use a different tool that "rakes" those hairs out.
Kinda... You don't "comb" it through like one, with stripping knives it helps you grab the undercoat and pull out. The outcome is the same, just different procedure.