That's an interesting perspective but mine is different. To me, adventure games and traditional FPS games start easy and then ramp up difficulty as you gain powers and gear.
Survival games, OTH, start out extremely difficult with your very survival always on the blade of a knife and only after you gain powers and gear does life become easier. This is what helps you feel the progression from "caveman" to "modern" quality of life. For example, you should be on the cusp of dying from starvation because of ineffective gear, food spoilage, and scarcity. IF you survive to the point where you have a farm, refrigeration, and decent hunting gear then the game becomes easier.
For survival games the first week should always be the most difficult part of the game with the greatest risk of death due to zombies, starving, dehydration, exposure, disease being at their greatest.
That's not to say that there shouldn't be new threats introduced later that will challenge the player but I've always viewed survival games as having an inverted difficulty curve.