I can't see where it's mentioned that the chosen medium is soil. But will give my uneducated 2 cents in terms of hydro and soiless grows.
In hydro a few days flush is a good precaution considering you spent 3-4 months growing it. I used to smoke solid for years, then it was replaced by green, I guess growing it was cheaper than smuggling it from morocco or whatever.
Some of it would taste very harsh, rank rotten and tear your throat/lungs up, the ash would be black and hard and you would often have your joint/bucket exploding/popping in your face. I've not really smoked that in years, maybe at the time a lot of now banned chemicals were used.
I think a few days flush for a better smoke can't do any harm. If you really need a smoke harvest a couple of grams.
Especially in hydro where, if you're like me, are feeding with copious amounts of chemicals. No pgr's but a lot of metals, etc found in micro for example. Maybe they're harmless but I think these were developed to grow food to be eaten, not herbs tonne combusted and inhaled (which forms whole new chemicals in itself )
I agree that your yield can be affected if you flush too early but you can read the plant and tell when it's stopped packing weight. I like a high cbd smoke or 50/50ish as clear trics give me major paranioa, strain dependant Ofc, so a late flush suits me and gives peace of mind.
evidence and research into the effects of using these chemicals is not exactly plentiful. In fact, the long term effects of smoking this weed are unknown, the old seedy cross pollinated weed the hippies of the 60s-80s smoked is a different game to what's been developed over the past 20 years
So being cautious before burning stuff and inhaling it can only be a good thing. Injestion and smoking can't be compared in my opinion. I can't imagine smoking a greggs sausage roll being as safe as eating one.
And if anyone for some reason, hypothetically, ended up smoking anything I had grown I'd be questioning my values and the ethical questions that go with it.
But if you and you alone are smoking your herb then that's your choice, it's your health.
Just realised how big this post is, pretty baked