Canie,

The dissipation has a vector which is both downward and in the direction of the continental drift. It doesn't matter whether it occurs over rugged terrain or smooth terrain, it still transfers kinetic energy from the tides toward the tectonic plate boundaries. No matter where it is dissipated, it transfers energy to the earth.

The ocean currents truly would be a minimal force. The force in sinking water is not even close to the mass times velocity of the moon (and the apparent motion of the sun due to planetary rotation.)

Dave