Re: Proposed Rule of Thumb
That may be something I said!
As the mass of an Earth-like planet increases, its gravity increases and mountains and even whole continents tend to have less relief.
As the Mass increases, the volume to surface are ratio increases and so the thickness of an ocean on the surface decreases - water depth is given by (volume * small percentage)/surface area
These two effects conspire to make water worlds more likely for high mass terrestrial planets.