Don't see much point in banning it, as people cannot get cancer from second-hand tobacco juice, but MLB has tried to de-emphasize it. It has been a part of baseball culture for a long time. Some pitchers used it for spitballs. A bubble gum manufacturer some years ago tried to sell shredded bubble gum as "Big League Chew." I have never taken to it myself, and found the need to keep spitting all the time really gross, but it has its attractions, I guess. I lost any interest when I saw a picture of a young and handsome athlete who had lost his entire lower jaw.

No point in lecturing people, because that never does any good anyway, but I hope people stay away from the stuff.