In PA, we have a lot of doe hunting in the early season. There are a few reasons:

1 - Don't shoot shed bucks
2 - Don't shoot pregnant does
3 - Eliminate the does that would be shot in the late season prior to the rut so bucks don't waste time and energy courting & breeding a doe that will get shot later
4 - Eliminate does that would be shot later anyway before they can eat a lot of prime feed - leaving the surviving deer with better nutrition