You can put both hemp and chemicals in factories, and factories operate with them, making a fine profit. So I really don't see this suggestion as necessary. In fact, there are some resources that actually need to increase their usage, such as gold.
if the only real use of chemicals is to put them into a pay and spray to get cash, they might as well cut out the middle man and pay you in cash instead of chemicals on those jobs.. Conversion businesses do exist but they arent profitable.
I don't find your "what about gold" to be a useful criticism of this suggestion. If you think that gold should have extra uses, suggest it and someone can reply "well can't you just use it in KLM business". If you are being consistent, then your argument also applies to your criticism. For the record, I do think gold should have some more uses, It's just not a valid criticism of this suggestion