Most important advantage is backlash
Rapids are still slow unless the machine is on frictionless linear bearings
You can have no backlash with an ACME thread. The penalty however is friction (or to put it another way efficiency).
Yes, it's all about the backlash but the reason why you pick a ballscrew over an acme is for the same backlash the ballscrew is something like 90% efficient while an acme is maybe 40% efficient.
Same goes for the rapids, the ballscrew means that you need smaller motors for the same speed (or more speed for the same size).