It solves the problem that you can only have on cabin (or two) in an elevator shaft. That's very inefficient in super-tall buildings. With horizontal travel ele

It solves the problem that you can only have on cabin (or two) in an elevator shaft. That's very inefficient in super-tall buildings. With horizontal travel elevator cabins can go out of their way and enable much better usage of elevator shafts. Further you become independent of the total length of the elevator shaft. So you drop another limiting factor to super-tall buildings.