You've just said that my examples were instances where prologues weren't necessary but then contradicted yourself by giving examples of why they could could be necessary in those instances and that confuses me.
I think those are instances where Chilari is saying you "may" use them, but again not where they are necessary. I agree. My preference would be not to use a prologue even in those instances, though I think those examples are better than some of the other reasons people employ prologues. I don't think Chilari said they could be "necessary" in those circumstances, but instead indicated an understanding of why someone might use them.