I've used these for 10-15 years. I've never had them delivered like that though. I've had them warp if I boil them up with washing soda in the Burco so I now use a lower temperature.
Plastic isn't the problem. Single use plastic and plastic waste is the problem. I note you' reusing a couple of poly nucs (and I have one). They last for decades (granted mine isn't yet a year old), and can be recycled when you're done with them so they're actually a perfectly good choice, especially given their advantages over wood.Isn't it time to reduce the amount of plastic we use or use biodegradeable alternatives?