I don't want a strap to soak up 50 percent more moisture than cotton. The last thing I want around my neck is a wet, clammy strap -- especially one that hangs onto moisture long enough to attract bacteria, mildew, and the smell that goes with each. I also want to put my binos back in the case when I'm done, without worrying about a bunch of moisture in there. In short, I want a strap made of artificial fiber that wicks moisture away quickly and dries out fast.
I'm a hunter. The only thing I want absorbing moisture is a towel.
Along the same lines, "biodegradeable" means it breaks down (as in rots) in nature. I want my bino strap to last -- and not start breaking down when exposed to heat, cold, sun, moisture, etc.
I'm all for being "eco-friendly" with some things, but I have my limits. I think one artificial strap that lasts for years is better for the environment than repeated manufacture and disposal of "eco-friendly" straps that have to be replaced periodically.
If you're lucky enough to be on private land and can leave your stand up during the off season you can tie an old piece of cloth or something of the sort to your stand. I like to use an old camo bandana that I have. That way the deer get used to the movement and eventually don't bother even looking up when there is slight movement. This may just give you the time to draw your bow or raise your gun without being detected.