hooking up heated seats w/ starter?

On Chevy and GMC pickups, the heated seats were not controlled thru data until 2003, so the relay method mentioned is the only way to do it.

As far as the resistor, I have never put it in. I don't know why it would be necessary either, since all the relay is doing is making contact between the same two points that the switch does when you press it, I cant imagine what the resistor would do. I am not saying that is incorrect to place the resistor inline, but it doesn't appear to be necessary, since I have done dozens of these integrations without the resistor, and haven't had a single comeback yet.

I would apreciate it if someone could explain what I am missing. I have been installing professionally for 8 years now, but the more I install, the more I realize that there is always something to learn, and better ways of doing stuff are always popping up.