This was inspired by this question. The topic as such is not necessarily opinion based and could be answered by citing scientific studies. But the author already has a clear opinion on the matter and is just looking for confirmation. I voted to close as opinion-based but I'm not sure whether this is a) the correct reason to close and b) whether this should be closed at all? As of writing this question had a negative vote count but so far no close votes.
I think it is fine to ask about arguments in favor of the (proposed) legalization of certain narcotics.
In your example, the question contains some of the author's opinion which in turn attracted down and close votes. That's fine, and it is up to members of the community to cast such votes.
Another option might be to edit out some of the opinionated parts. As long as the author agrees to that (i.e. the edits aren't reverted leading to an edit war) then that's fine as well.
If the author stats reverting such edits because they don't agree with them, then it might be better to take a step back. That doesn't happen often, but when it does it could be cause for voting (down or to close) or flagging it for moderator attention (if the edit war persists).
So in my view, it's up to the community to decide what to do with the question. I don't see a reason to mod-hammer it one way or another.