Some refrigerator manufacturers also state in their installation instructions not to use them. It is not uncommon for those tiny valves to deliver inadequate water supply to the ice maker. This causes all sorts of problems and headaches. In my opinion, the best way to install an ice maker supply line is to treat it like any other fixture branch. Install a standard tee fitting and a ball valve that will allow you to shut off the water supply to the ice maker without disrupting water to any other fixture in the house.
Ball valves are superior shut-off valves.
There are no washers to replace. These fittings are readily available at plumbing supply stores, hardware stores, or home centers. I have also heard that hot water freezes faster than cold water. But I have always doubted it to be true. So I ran a controlled experiment on your behalf.