Agreed. I could poop in a bag, let it dry, grind it up into a powder, and sell it on Amazon as an "all natural" supplement. It would be cheap too, because the cost to me is zero above what I'm already paying from food. You don't know what you're getting in terms of quality when you're buying on the cheap.
You get what you pay for. I'm sure as a supplement, Gromwell Root has benefits, but when you're tackling a major assault on your body, such as Covid infection, why tackle the virus with a BB gun when you can have a 12-gauge shotgun instead?