Probably never, entirely. More or less, in other times and places. It seems like a useful dividing line for proper vs improper laws.
And until your side gets enough people who want to legalize it, that's where it stays.
An "argument from authority" (majority rule)?
Might makes right?
Never in the history of the world, by any society or government (including our own), have laws been limited to controlling behavior which harms others. I see no reason to suddenly apply this standard to recreational drug use.
"It seems like a useful dividing line for proper vs improper laws."
Not really. Define harm. If a man exposes himself to your wife and daughter, has he harmed them? Certainly he shocked them. Insulted them. Disgusted them. Offended them.
But if you include those definitions as "harm", well, we've really opened things up, haven't we?
"An "argument from authority" (majority rule)?"
No, not at all. Through the legislative process. People expressing their will through their elected representatives who vote in various chambers, then signed by the executive, and approved as constitutional by the judicial.
You don't believe in majority rule, do you -- what some have called "mob rule"? Of course not.
Then certainly you're against the medical marijuana laws passed in 9 out of 11 states by public referendum rather than through the legislature? Glad I can count on your support to overturn those laws passed by those "mobs".