Vitamin E isnt cheap compared to a bottle of Crisco,,, I suspect they were cutting all of the juices with any thick cheap oil
Vitamin E was likely a gimmick at first
While I like me a good conspiracy theory bedtime story just as much as anyone else, I'm inclined to strongly agree with this statement, and that it's no conspiracy.
The equation is simple:
1. Take a safe but expensive, legal (in places) intoxicant.
2. Cut it with anything that will not reveal visually that it's been cut
3. Sell it for the same price, or more, as the real thing
4. Profit!
Any barrier to entry for makers is so low you couldn't crawl under it. They don't need special materials. They don't need a commercial lab. Just some seed money to buy the materials and start making stuff wherever there's a flat surface to pour liquids.
Your theory also rationalizes the slow information flow on this apparently fast moving topic. The reason they can't pin it down is: there's probably as many different contaminants, at all kinds of toxicity levels, as there are people making this crap in their kitchen.
Then there's the consumers. If they even know there's a problem, when did you ever hear of anyone interested in consuming any substance actually heed a health warning? They've been printing one on cigarette packages for decades. The THC angle just makes it worse.