Polyethlene hose is a disaster waiting to happen. Most codes now
forbid it. If that's what he's talking about, he's right. In addition,
the preferred way to plumb an ice maker line is to mount the shut off
valve as close to the fridge as possible. That prevents just the sort
of mess that aemeijers was talking about.

I hadn't heard of a shut off box behind the fridge, but it makes a lot
of sense.

Way too many cases of flooded kitchens and mold caused by bursting
plastic lines.