The threads on my Chucks are doing great after over 20 months.
But I recently got a Reo Mini and it says to put some Noalox on the firing pin.
So I guess that is for protection from oxidation?
Primarily, yes. It helps keep dust and sediment from getting ground up in the threads, which can ruin them over time, and does prevent metals from oxidizing. Since opening it up to swap batteries is something you do frequently, and since you take it out in public and use it all over the place, there's plenty of chance for the threads to get a little dinged up and tarnished over time. Noalox helps protect against that and keep the threads meshing smoothly.
Sure, if you baby your gear (as I tend to do) you probably can get away without Noalox and you'll do just fine. But I don't like to take chances if I'm shelling out good money on something I can't go out and replace on short notice.