The main forces that keep the water on the surface of the planet are connected with plate tectonics. If the plates were to stop moving, the water probably would eventually be absorbed into the interior, although this process would take a very long time indeed.
Are you saying that there is an advantage in having that tectonics? They say it is not good to live near because of possible earthquakes. However on this post, it says it was an advantage for ocean to stay.
It was an advantage before when we do not have enough waters. As of now, it is not an advantage because of the changes it caused too much water in the ocean already and you are right, because of the possible earthquakes in areas that has active tectonics.