I've had the same chain on for 10+ without any concern.

Think of it this way. Look at motorcycles and think of the stress that is put on that same chain and how long a chain lasts. The amount of stress that you put on the chain climbing is very small compared to the stress that a high torque/horsepower motor will. Even if you climb 100 times a year as long as you are doing maintenance on it it should last the life of the treestand and probably you.

Also, the tubing is there more for the tree than the chain. It's supposed to keep the chain from digging into the tree to protect from tearing the bark off and damaging the tree.