I'll bet that all your answers and things you found in that research, is from nutrient makers or those who owe them something.
In reality, nothing in growing/farming gets a "flush"! NOTHING, and that includes any tobacco product! Including cigar tobacco's that can reach per "stick" prices of over $25.00 each.....
For tobacco, it's all in the cure. In Holland, they grow hydroponic tomato's for much of the EU.....They don't "flush" those either....
I don't understand a "pure environment" in your context. I build and recycle my own soils. The plants I have running in bloom right now, are in soil that has been re amended and re used for over 3 years....No buildups, no burnt plants, no problems! If your confusing the cleaning of a hydro system after a run. That's totally a different thing!
I understand the difficulty in "wrapping your head around" this new idea (to you). I suggest you simply try a plant done that way. Run it out by feeding normally to the last cpl of weeks. If you hit it with high P&K supplements. Stop that at that 2 weeks left and normal feed it out to the end. I stop all nutrient a cpl of days ahead of my harvest. It simply saves me the cost of the nutrient, because the remains of it in the soil. Will carry it out that last few days.....Not a fade either!
Dry it at 50% RH in an area of 70deg F.
Dry till you can bend the stems and they "crack" and not simply bend and not crack.
I then jar. The jars have 62% Bovida packs in them. I open the jars daily for a week. Say a few minutes while I water and screw them tight again. Do this for a week.
Then set'em and forget'em for 5 more weeks and try a bud or 2. Let some go another 2 weeks and try that...
If the material gets under "like" 54% RH, it quits curing....
Silica use makes for dark and hard ash.
Uncured sugars make for bad tastes and "crackling".