That means that if a local farmer wants to sell hyper-organic meat that doesn't have certain USDA-mandated chemicals, they should be allowed to as long as they don't export it across state lines.

That also means that if Pfizer wants to make a drug in my state and sell it here, I don't want the FDA involved. I'll take the bad with the good.

While we're at it, I don't see anything in the constitution about banning Marijuana either, I think they do that under the modern reading of the commerce clause too.

Sure, but you're really only mandating 50 factories instead of banning them.