> This both increases the maximum payload mass of a launch system and allows for the miniaturization of launch vehicles so they may be used as nano-launchers for the rapid access of small satellites to low-earth orbit.
As I said, it reduces problems of SSTO (Single Stage To Orbit). The problem of SSTO is low payload mass to the size of the rocket and fuel necessary to transport it. The main solution to this is having multiple stages. Which comes with its own problems -- multiple engines, complexity, more points of failure, etc.
But in the meantime SpaceX learned to reuse the stages so suddenly the problems are no longer as much of a problem as they were before.
> This both increases the maximum payload mass of a launch system and allows for the miniaturization of launch vehicles so they may be used as nano-launchers for the rapid access of small satellites to low-earth orbit.