The leafly article states:
In legal state-regulated markets, vape carts undergo mandatory lab testing to insure potency and purity. But in the illegal markets, anything goes. As a result, some consumers of illicit carts have learned how to spot watery oil cut with traditional propylene glycol, vegetable glycerin, or MCT oil. Without the assurance of lab testing, vapers often judge the THC potency of a cart by looking at the thickness of the oil in the chamber. Thick oil has become a proxy for purity. Thin oil is a red flag.
so these assurances are not intended for the end user. They’re intended for the distributor, who can now get away with more cutting. This would cut into my earlier speculative argument about antioxidants, but hey.
(since I don’t vape, or indeed consume THC or nicotine, I’m judging these sorts of articles by how much they appeal to my sense of cynicism, and not against actual experience)