On top of that, they are trying to do it with the main engines, combined with the light weight of the almost empty stage..the power can only be reduced so much.

On top of that, they are trying to do it with the main engines, combined with the light weight of the almost empty stage..the power can only be reduced so much. They can't hover and stabilize. They literally have to have a landing burn that makes the velocity at height 0... = 0. Which is incredibly hard enough on stable ground, even more on water. Maybe they'll figure out how to cut off engines as the stage slows down so that the acceleration change isn't so drastic and it could actually have a miniature 'abort' land. Where it would go back up slightly to re position itself in the event of weather, wind, rough waters, etc.