Dealing with your climbing rope at the crag is often a tangley affair. Most rope bags are some sort of sack that holds a detached tarp. While you’re climbing, the tarp is out of the bag with the rope piled on top of it, protecting the rope from getting dirty or wet or snowy. But when it’s time to move to a new route, the rope has to get rolled up into the tarp, which then has to be stuffed into the sack. Often, wrestling of said sack and rope and tarp ensues, which can cause rope tangle by the time you get to your next route.