[tasuki]

The starter has a mostly similar percentage of water. And there isn't that much of it anyway to make a significant difference.

I'm not that experienced with baking, so take the above with a grain of salt!

[giraffe_lady]

Once you're going for consistent loaves eg selling them to people who expect them to be the same every day, you do have to factor in hydration of the starter. Usually you keep it the same as the dough for simplicity but there are reasons why it might make sense for them to be different.