I think you do need them on Nameless Isle but there are hundreds lying around and you can skip that bit anyway if you want.
You don't, actually!
I'm assuming you're talking about the Elf sanctuary. You can go around the side of the Elf place and there's a ledge you can teleport to with C&D, Tact Retreat, etc. and then throw the rope down to easily navigate up and down that ledge.
I stumbled in there by accident on my first play-through and saw that rope coiled up on the ground. Instantly knew I could teleport up there and sure enough, it worked!
