Your right as RAIN.
However, I think the [flushing] is centered on indoor growers.
They use many chemicals that outdoor growers would never use.
So in their case, I would flush.
Flushing is no big deal.
It has been HOT here in the L. a. area.
My plants that face West have many shade leafs that have turned yellow.
No longer growing and of no real use I cut them off.
More sun now reaches the inner buds.