bad configurations can be selected against inside the germinal cells themselves or when the new organism is just a clump of a few thousand cells
Many genes and downstream effects are only expressed (and can be selected on) after birthing/hatching, or only in adult organisms. This can include whole organs, e.g. mammal fetuses don’t use their lungs in the womb. A fetus could be deaf, blind, weak, slow, stupid—none of this would stop it from being carried to term. An individual could be terrible at hunting, socializing, mating, raising grandchildren—none of that would stop it from being born and raised to adulthood.
There’s no biological way to really test the effect of a gene ahead of time. So it’s very valuable to get genes that have already been selected for beneficial effects outside of early development.
That’s in addition to p.b.’s point about losing information.
Many genes and downstream effects are only expressed (and can be selected on) after birthing/hatching, or only in adult organisms. This can include whole organs, e.g. mammal fetuses don’t use their lungs in the womb. A fetus could be deaf, blind, weak, slow, stupid—none of this would stop it from being carried to term. An individual could be terrible at hunting, socializing, mating, raising grandchildren—none of that would stop it from being born and raised to adulthood.
There’s no biological way to really test the effect of a gene ahead of time. So it’s very valuable to get genes that have already been selected for beneficial effects outside of early development.
That’s in addition to p.b.’s point about losing information.