I don't subscribe to most of the conspiracy theories you will read about on these forums and others. To be effective would require of the conspirators an efficiency and competency that government rarely if ever displays. I do however believe that government employees eventually seek to preserve and expand their own power base, at the expense of their original remit.

I also am a firm believer in the law of unintended consequences, by which the actions of government tend to have consequences that were unforeseen, and often make the "cure" worse than the "disease." In this case, clearly (to me at least) unadulterated marijuana is not dangerous enough to justify any regulation whatsoever. With respect to possible adulterants, without the rewards inherent in trafficking in a black market substance (which marijuana still is under the current regulatory scheme because of the "medical" sham) there would be no reason to use any such adulterants to stimulate growth or kill pests. Once again, an example of the law of unintended consequences.