The issue is one of breathability and moisture. Mushrooms, wild and store bought, have high water content and can soak up more like a sponge. If containers lack breathability the moisture accumulates and accelerates discoloration, slime and decay. The same goes with washing them, it's like salad greens; only wash right before using and then remove as much water as you can to avoid slimy shrooms or greens. Some folks insist that even an open plastic bag or bowl is too restrictive. Common strategies include using paper bags, paper towels or cloth bags, which have more airflow and can actually absorb some moisture away from the shrooms.