'Counterfactual History' - what a nonsensical piece of jargon. The implication is a branch of history which is 'against fact'.
If it does as it says on the tin, then there is no place for it anywhere. It is simply fiction.
'Suppositional History' or 'Speculative History' on the other hand, most definitely does have a place, but only when it based on accurate fact
Significant turning points in history cannot be grasped properly, or even identified, without speculation about what might have happened, if the causal facts had been different.
Take for example, the absence of evidence for a Roman invasion of Ireland (
) - we know that we on this little island were not part of the Roman empire.
But what would we be like today, if we had been part of that empire? That's worth thinking about and discussing. That is how we come to understand the significance of the event (or lack of).
There is no reason why speculative history should be any less informed than its alternative - whatever that is, 'Factual History'?
'What if?', to my mind, is one of the primary motivators for any interest in history. How things might have been different, can tell us a lot about how things were.
To categorically rule out speculative history would, in my opinion, make the subject very, very, very dull indeed.
As regards how this might apply in this forum, I think it is simply a question of the mods' judgement, but I don't think an update to the charter is required.