Anything calorie dense (and therefore hyperpalatable) is easy to over eat. Fat is twice as energy dense as carbs or protein, so it adds a lot of calories. Put a tablespoon of olive oil into the skillet, and you're adding an empty 120 calories.

Typical foods you could eat 4000 calories of combine fat and carbs into a delicious combination: french fries, pizza, cookies, milkshakes. I don't look at those foods and think individually carbs or fat is at fault. But on the other hand, carbs are what the body uses for energy, so to avoid them doesn't make sense to me. I'd rather skip out on fat.