In fact I cannot find Buddleia in my perfumery books. This plants produces a pheromone which attracts butterflies and as we know, there is not much difference between pheromones produced by insects and by mammals (see //attarperfumes.net/olfactory-communication/pheromones-part-4-human-pheromones/).
There are very few flowers from which an essential oil or absolute can be extracted, the problem is mostly tecnological, but in many cases the smell of the aromatic raw material extracted is not worth the work to extract it, when you try to sell it.
In other cases the cultivation is not viable or would require too big spaces and too much labour cost.

AbdesSalaam Attar
Compositore Profumiere