Interesting theory. I guess I could try it and find out in one or two hours.
One thing, luck does improve drops. I was at 20 and never lacking grasses, other stones, etc. I still don't have a pure bladestone though.
The developers did a disservice to the game by not having an easier way to get a pure. They should have wanted people to actually be able to use +5 sharps. Farming for the pure is awful and kind of makes me hate the game. Maybe I should blame trophies?