The site seems to suffer from frivolous moderation (closing questions as "opinion based" or "duplicate" or "off topic" without providing valid reasons), with lack of accountability and clear moderation policies.
The root cause I believe is a conflict of interest. Users who racked up reputation score sufficient to close questions are rarely ones with any moderation experience. This invites bias where users interested only in answering simple (for them) questions would close ones they have no experience in, or ones that take more than a minimum effort to answer.
I believe this is what happened in this case (read the comments for some context). This happened to me and to others more than a few times, and is likely a systemic issue:
Inappropriate opinion-based closings
This is regretful.
P.S. Moderators and I exchanged a few comments under the question, and most of them (all of mine and some of moderator's) were deleted w/o notice or explanation. Those deletions are also not showing up in the question history - at least not in one visible to me.
So in addition to closing a question as "opinion based" and then explaining that it was actually closed for a different reason ("hypothetical question") - the comments get deleted w/o notice or explanation either.
What a great site this is! :)