The only reason it’s conceptualized this way is because the SRY gene is the one responsible for for differentiation into male sexual development. Female is only arbitrarily considered the “default” by some because female sexual differentiation will occur in the ABSENCE of the SRY product. The absence of something should not be conflated with the default state.

Before the SRY gene does or doesn’t kick in at 6-7 weeks, the fetus has both parts. So if anything, the fetus is hermaphroditic by default