I have seen related questions been asked on this forum, but none of them actually reached the point I would like to be clarified. From my perspective, every single non-math/logic question is opinion-based. In some cases, that opinion will be strongly backed by evidence. In others, it will be an intuition with not too much justification. However, there is always a chance of every answer being wrong (the only verifiable truth is, as Descartes put it "cogito, ergo sum")
My question would then be "where's the barrier?"? How certain does science have to be about an answer in order to stop being opinion-based. Let's show a few examples:
First, our all time favourite: a code question I posted myself on stackoverflow: Is it possible to label elements in a Python list? In this thread, I am asking for a way of writing a "Python list with labels", this means, a "Python dictionary", but there are other ways to achieve the same goal. Most people would not say this should be put on hold as opinion-based, but in that case... Why should the following question?
Classical Chess Opening Repertoire This question was posted on the chess forum. For those who may not be familiar with chess, the asker wants to build an "opening repertoire", so, he wants other users to help him find the most adequate answers to the opponent's first moves. But there is no such thing as the most adequqate answer! There are many possible ways to reach a good position, just as in my previous question. So, yes, the answers to this question are purely opinion-based and it was put on hold.
However, How to beat King's Fianchetto Opening Modified (White) this quedstion is asking basically the same thing, except it a different position. As before, there is no final answer, and indeed we see different people giving different pieces of advice. The question was not put on hold and it even received 4 upward votes.
Just in case you know nothing about either Python or chess, here are a few examples of questions that could be opinion-based (or not)
In short, my point is that opinion-based judgements are purely a matter of opinion and this should not be a reason to put on hold so many questions,at least, not in every community. I understand I could be wrong and that's why I ask you: "Where is, in the Stack Exchange world, the border between a fact and an opinion?" Please don't put on hold as opinion-based!