Smoking or vaporizing is something that people choose to do for extended periods of time, and doing so in an enclosed space, especially many people doing it at once, can fill air in that enclosed space with the byproducts, which may be harmful.

If people drank something that made them burp constantly, permeated the air with the smell of those burps, and that vapor was harmful, then absolutely that should not be allowed (beer does not quite count; you don't generally burp continuously while drinking it, though it may cause an occasional burp, and it doesn't cause a lingering, carcinogenic vapor to permeate the space).