I liken this technique to using the sous vide. Can you cook a perfect medium rare or rare steak without sous vide? Yes. Is it way, way, way, way easier to achieve with a sous vide? Yes.
I use a similar technique with breakfast sausages in casings: boil them in water for a bit, drive off the water in the pan, sear them a bit. Turn out great.
As one who eats not that much sausage because I like leaner meats, this technique could help me cook them correctly on the grill. I think this year so far, I’ve grilled hot dogs and sausage maybe twice, and it’s so easy to overcook them, especially on a gas grill you use a handful (or two) of times per year. With this technique, there’s a lot more leeway.
It’s like when I make pulled pork (or brisket) by using the sous vide to cook the meat, then plunge into ice water, put in the fridge, and then smoke over charcoal for not that long. It comes out perfect and is way easier than trying to cook for 12, 18, 24 hours or whatever it is you’re supposed to cook it for.
It’s probably overkill if you use your grill every weekend all year long, but for me, I’m looking forward to trying it.