I think it locks you in on where the arrow will go,, if there is no rest,, you can experiment up and down a bit and see if there is a sweet spot,, then put a leather rest if you want,, being able to move the placement of the arrow rest gives you some tuning flexibility that a cut in rest will not,, and I dont see any advantage to cutting in the rest,, if thats what you like, it can work fine,, I see some nice bows with them,,