it is a myth. blind taste tests show that people cannot tell the difference.
if it is "harsher" what is the cause? because true believers in this myth used to purport, falsely, that it reduced mineral content in the buds, but analysis of plant material shows this is completely false, incontrovertibly so. It does not change the chemical make up of the plant, because that is controlled by the DNA, for fuck's sake. things cannot be made differently. there is a specific molecular recipe for all key components to cellular growth.
flush if you want.. but it is not value-added. What you see is people clinging to old anecdotal knowlege that was not ever verified or proven. when someone did look into it, it was overtly bullshit. think about outdoor plants. do they taste bad because we don't flush the earth of all the nutrients in top several feet of soil? no.. that would be proposterous to even try.
"organic" is a bastardized science term used in marketing ploys. even in chemistry, it doesn't really mean much on its own. In fact, the definition had to be changed at least one time when we first synthesized an 'organic' (real use of term) molecule in a lab. The term is earth-centric and likely based in hubris.
organic molecules can come from inorganic sources. this happens in the plant as it uses CO2. CO2 is inorganic molecule. The plant is swimming in inorganic molecules and could not live without them. the perception on this topic is simply the results of people with zero knowledge making assumptions and extrapolations about things others have already learned and verified. Instead of using that existing knowledge, they guessed and guessed very poorly... or realized it illicits a respons in people that allows them to price products higher.
life is more ordered than that... when you eat a bunch of pizza you don't have a pizza brain, right? your bones don't turn to peperoni, right? LOL