Not entirely true, because nearly anywhere in the desert if you wear full cold resist you will get heatstroke. That’s the biggest portion if the map. You can wear full heat resist armor anywhere except the snow and get no higher than very cold.
When I said most armor was cold resist I should have been more clear. I’m not taking into account armor with survival because it’s worthless and has no situation in which it does something better than other attributes. Also you could go even further and count the other bad armors, but I was just excluding survival bonus