This is an idea that makes sense. Smoking through the mouth may have become a thing initially to protect the face from biting bugs. The native did it all the time. Both men and women. Tobacco was a valued item. One convenient way of keeping any old material smoldering is to blow air through it. Often a smolder can work on its own, but a tight, fast-made, mobile smudge may require an infrequent prime of blowing air.  Holding the smolder in your mouth may have been the most convenient way to also free up your hands for work.  Early smokers may have found that the negative health effects of having the primitive cigarette constantly in the mouth didn't outweigh the effect a cigarette would have on deterring the bugs from biting the face. We literally evolved a calm feeling with sticking a smoking stick in the mouth. Drifting smoke also shows immediate wind direction, a boon for hunters.  I don't smoke any sort of material, nor do I recommend you start.