Not really. When you drive on rocks the last thing you want to have is to bounce over the terrain. As fully inflated tyres have a very small footprint, they don't have much grip and it is more difficult for the car to get over the rocks. As a result, the car may bounce up and down and you can lose control and slide to a rut causing damage. When driving on mud, you get more traction with deflated tyres. The smaller your footprint is, the deeper you are going to dig in the mud. With a longer tyre footprint it is less likely you dig down the mud.