why is a cast iron skillet only oven safe up to 350 Fahrenheit (176 Celsius), it's iron! that's strong stuff.?

I don't know where you got this info. Cast iron's melting temp is 1,700F. Cast iron skillets are safe to use in your oven at 500F w/o warping. When I bake a pie I put an iron skillet in the oven upside down and preheat the oven to 500F. I then put the pie on the iron skillet and reduce the oven temp to that required for whatever type of pie I'm baking. The hot skillet quickly cooks the bottom of the pie shell and makes it less soggy. In fact I sometimes clean my cast iron during the cleaning cycle of my self-cleaning oven. The temp during cleaning is about 600F. Before I had a self-cleaning oven I cleaned the skillet (The out side of the skillet gets kinda groady after a few years) in the coals of a camp fire. Even the enameled cast iron cookware made by Le Creuset is safe at those temps. The exception is a wooden handled cast iron skillet. These skillets should not be used in your oven.

Cant iron can go well beyond 350F. I have several skillets and use them all the time in the oven, never had a problem. Maybe the concern is that it could do something to the seasoning on the pan itself? Thats the only thing that comes to mind, but even that I cant see being a problem.

I have never heard this for a solid cast iron skillet. I have been using mine for many years in all kinds of temperatures in the oven and have never had any problems whatsoever .Where did you get this bit of information?

i have a lodge cast iron skillet and have used it up to 450 in the oven baking corn bread in it

It seems odd.

It might be because of coatings like teflon or a pre-cured surface if it has that.

The only other thing I can think of is if it has synthetic handles or something.