The design is sound, just not the order of assembly shown. For the bench, the lower bricks are suspended by the upper ones, so would need to be assembled separately before connecting to the legs.
True, easy for a human, not so easy for a robot to go through those extra steps. I wonder if they made it work with the robots, because in the video they only show the robots building from the bottom up.
Still, I think you wouldn't find such a design in actual Lego set, because such floating bricks make the construction weak.