I just ordered my first hammock (Warbonnet) and I've been looking at tarps. I've seen a lot of very nice ones for a good chunk of change. Just out of curiosity, why aren't more people using just regular blue tarps like the kind you get at Walmart? Aside from the UL tarps, the Walmart ones are roughly the same weight per area as many, if not most, of the more specialized ones. Just wondering if I'm missing something? Help a newb tree dweller out.