I propose making questions about counterfactual history (e.g questions of type "Suppose that such-and-such development in the history of science and math did not happen. What would be the ramifications?") of Science and Mathematics explicitly off-topic here, as it is done in History Stack Exchange. Questions on counterfactual history almost inevitably lead to opinion-based answers.
Edit. I did not think I had to spell it out, but given the current answer, I think, I should: There are general Stack Exchange guidelines against "opinion-based questions" which is explained for instance here
primarily opinion-based — Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.
This does not meant that opinion-based questions are bad per se, they are just are a bad fit for Stack Exchange sites (in contrast, for instance, quora has plenty of these).
There were many proposals for having some kind of "parallel" SE sites for subjective questions. They were shot down, see for instance here and here.
(To the above, has various caveats, such as "metas" in SE are designed for collecting users opinions. But I am not writing a legal document here...)