Galah
How appropriate.
Without this form of clearance, half the world outside of sleepy Oz, would not function. The alternative is to wait until the landing aircraft has passed the aircraft to line up. Time for the clearance + time for the acknowledgement+time to spool up and get the beast moving+time to taxi at an appropriate pace and get properly lined up (some aircraft you can't just poke up the power as you roll on, due to trucks off centre), all adds up and the guy at four miles is starting to get twitchy. At least with this clearance the PIC has the ability to anticipate and get moving quicker. Its all about flow control.
As the good Kaptain said, works well in the real world. How about you enter the time warp and catch up.
GG