If you suggested putting tobacco in your joint over here on this side of the pond, you would be laughed out of the circle. Seriously, I've never heard of such a thing.
There's no need to cut weed with tobacco to weaken its potency. Just take smaller hits of the pure stuff. That way you get all the flavanoids of the weed without any of the crap smoke from the tobacco.
It sounds to me that this is just a cultural preference sort of thing, and that there's no real practical application for adding tobacco beyond that's what you enjoy.
There's no need to cut weed with tobacco to weaken its potency. Just take smaller hits of the pure stuff. That way you get all the flavanoids of the weed without any of the crap smoke from the tobacco.
It sounds to me that this is just a cultural preference sort of thing, and that there's no real practical application for adding tobacco beyond that's what you enjoy.