they certainly do. And to keep the flavor the same from pack to pack. And to keep nicotine levels the same from cig to cig. Funny that people complain about batch variations but that's pretty much an effect of how much less severely processed pipe tobacco generally is. But as anyone who has been stabbed can tell you location is very important and makes a critical difference in short and long term health. The lungs are simply way squishier, softer, and sensitive then the lining of the mouth.
Also no matter how much you suck smoke into your mouth whatever you get out of it is going to leave your system where as your breathing tubes and sacks will get clogged with tars and other things. Basically not putting it in your lungs makes a very huge difference.
Though one of the ones that is dangerous orally would be pan masala which can have tobacco and betel nut. And anyone who's tried that will talk about how much it rips up the mouth.
Basically cancers are caused by cells being damaged and thus repaired at more rapid rate. Eventually the copies go bad. Your lungs are going to need to replace more bits from inhaling smoke then your mouth is from having some smoke in it. Just how it is.
