If you quit giving nutes two weeks before harvest and just water with plain pHed water you won't need a flush. I'm assuming you used high quality soil without time-released nutes in saying this.
Preharvest flushing puts the plant(s) under serious stress. The plant has to deal with nutrient deficiencies in a very important part of its cycle. Strong changes in the amount of dissolved substances in the root-zone stress the roots, possibly to the point of direct physical damage to them. Many immobile elements are no more available for further metabolic processes.
