Whether it happened or not was never the focus except for
critics. What was always important was that it was used as an
extreme example of obedience - an unthinkable scenario. It's
even more vivid in the case of Job. If you go through the
teaching and theological texts through the history of the
religions, this story was always used as an example with which
to debate and discuss and compare to one's own life. Could you
do it? Would you do it? Whether it happened or not wasn't
questioned because it didn't matter. What mattered was the
lesson it gives. A thought experiment. Then again, I find nearly
all thought experiments ridiculous beyond a certain point: How
many people use examples from movies (like the Matrix) to base
their real lives on? But that's my bias.