Assume you have 100g of flour at equilibrium 20% ambient humidity, and the same 100g of flour at 80% humidity.
I don’t know how different the effective moisture content would be, but measuring the weight of the flour to the gram seems like you’re including the moisture in the weight of the flour. Maybe one packs denser on a scoop. I don’t know. But I don’t necessarily think it’s more accurate.
On the other hand, it’s really easy to just pour in 540g of flour, mix in a shy tablespoon of salt, 280g of water, and a good glop of starter. Far easier than trying to get consistent scoops or measure to the meniscus in a liquid measured.