Perlin noise (with octaves) can generate quite natural looking terrain height maps. But it doesn't simulate natural processes such as wind and water erosion and

Perlin noise (with octaves) can generate quite natural looking terrain height maps. But it doesn't simulate natural processes such as wind and water erosion and plate techtonics. For example, plate techtonics tends to create mountains ranges in lines (such as the Himalayas and the Atlantic mid-ocean ridge) rather than completely randomly. So I guess that is going to limit just how natural it can look, especially over the scales that these natural processes operate.