I once had some frozen foods delivered to me in a paper/cardboard box. There was ice around the frozen food, and it had melted partially, and the water had made the bottom of the cardboard box soft and mushy. When I lifted the cardboard box, its bottom tore, and my frozen foods started poking out. A plastic-like bag would not have tore due to wetness/water, would have been be a lot thinner, lighter, and not required any dead trees to make. If it were biodegradable, there no major environmental concerns either.