I'm not sure if it was so much the flavor profile as it was being used to thin out the product using an inexpensive thinning agent. THC concentrate is very viscous, and needs to be cut with something to be viable for cartridge use.

Iirc terpenes are used in higher quality products.

From what I've read, the primary goal was to cut it without thinning it very much, in order to pass the "bubble test". Consumers would test viscosity by observing how quickly the airbubble in the cartridge moved. Vitamin E acetate is thick enough to deceive people into thinking the cartridge wasn't cut.