benefits of creating a levain?
I've been making sourdough for a couple months now, and have been trying to expand my skill set. My most reliable and most used recipe is:
545 g bread flour
36 g Whole wheat flour or rye
75 g starter
13 g salt
365 g water
This recipe calls for you to just mix all the ingredients together in the first step and go straight into folds and bulk. I've performed an autolyse with this recipe which creates a nice product, but is not necessary for great bread still.
I've recently purchased a sourdough recipe book, and every recipe calls for a levain to be made in advance, rather than just dumping the starter in with the rest of the ingredients. Is there any benefit to creating a levain versus just using my 100% starter in its place, gram for gram? I guess I am just confused as to why they're seemingly creating a second starter when they could just use the starter they already have?
TL;DR- why do some recipes create a levain with their already mature starter, and can I skip this step by replacing the levain in the recipe with 100% hydration starter? (assuming the levain is also 100% hydration)