Not nessesary, but they are a HUGE advantage. Your off the ground, where it is often cold and wet,and the deer really can't easily see you. It gives you a very wide field of view, and Ive heard that deer really cant smell you either. Its kinda bad because its pretty dangerous, but thats why they invented harnesses. Depending on what kind of stand you use and where you hunt, it is a drag to get it through the woods, and in some places, tree stands are illegal. On public land, you cant build a permanent one, and you cant use the spikes that serve as ladders to get into the stand. But, my dad got a monster 11 pointer from the ground. They all have their advantages and disadvantages.