Always thought this was a dubious
practice
So you stay on the ground beyond
the computed VR building speed
to assist with any wind shear encounter
But what if you encounter a major wind shear while you’re still trundling down
the runway ?
If it’s significant enough you could be in a
situation where you don’t have enough
airspeed to lift off but your groundspeed
is too high to stop if you unwisely chose
to attempt to
I’d rather be in the air (where aircraft are
meant to be) with speed and some altitude
and go straight into the windshear recovery
maneuver, your odds are better