Don't know why? But I have hunted a string D loop for a couple of years now. you can hook up quick enough with it. The more you use it the easier it will become.

As far as draw length, putting the loop on does not change the bows draw length it merely changes the position of you hand while at full draw. If you find that you hand is to far back you can shorten your release. If you can't get it short enough then you can physically shorten the draw length of the bow, by twisting strings, changing cams or what ever. When I went to the loop I just simpley got used to a different hand position at full draw.. It moved back the distance of the loop...