I need to connect my household water supply to my new Frigidaire refrigerator, using 1/4" copper tubing. The kit I bought from Home Depot contains a self-piercing saddle-type shut-off valve. However, the instruction manual that came with the fridge says "DO NOT use a self-piercing type shut-off valve". Why, what is the downside of this type of valve?

They are not the best to use but I have them on my icemakers with no problems.

Here in Plymouth MN SADDLE VALVE self-piercing are not code, have to use solder type. I went to plumbing store they would not sell them. Not plumbing code