Absolutely agree flushing removes those heavy salts built up within the root zone ... if you ever dry your NON flushed plants and smoke the herb kn a joint carefully inspect the color of your ash if it burns dark or grey it's still contains those minerals and heavy salts because flush hadn't had the chance to remove them from the root zone leaving them inside your product.
A good flush is 100% key to a quality smoke less harsh and more smooth when flushed correctly.
Dont beleive us is fine but check out the ash on a joint is it pure white from flush or is it grey and dark... it works neat stuff