@lololulu19 Elon says
The strong gravity of Earth makes the physics of a fully reusable rocket with positive payload margin extremely difficult to solve, which is why it has never been done before.
Removing the mass of landing legs from the booster and ship by making the tower do the work of final velocity attenuation greatly improves payload margin.
This architecture also simultaneously substantially increases launch cadence, because the same arms that lift the booster and ship onto the launch stand also catch them, allowing immediate placement of the booster back on the launch stand and the ship back on top of the booster.
tldr; It's meant to be economic & if it isn't yet, oh it will be.
("also simultaneously substantially" - ugh, is that bad writing!!)
The rocket returns, yes RETURNS, to its intact launch tower.
