One of those situations where the variables are too numerous to allow an accurate theory.
It was easy when we knew of only one solar system and even our formation is only theory.
It’s a common problem to a lot of areas of modern science: they can only make a viable theory by extrapolating beyond the scope where it would be reasonable to extrapolate. Now, the sensible thing to do in that situation would be simply not to extrapolate. However, if they did that, they would not have a theory to explain many things, and nobody will give them funding for NOT producing theories.