Yes, that recipe is correct.
Hydration at 100% or above comes down to the protein content in the flour. Higher protein flours can absorb up to 30% more water than a lower protein flour.
That’s the reason the recipe specifically states a high gluten flour. You need a protein content of around 13.5% to 14%.
A good quality unbleached bread flour should get you in around 13.5%.
To get to 14% gluten you’ll need to use a whole wheat flour.
Whole wheat flour in fact requires at least 100% hydration. Bakers frequently make the mistake of under hydrating dough made with whole wheat flour.
Since high hydration dough is too soft to knead, you have to use either stretch and fold or slap and fold to develop the gluten.
High hydration is used to achieve an open crumb. And there seems to be this obsession with the big holes in bread. And so bakers have been taking the hydration levels higher and higher.
While hydration is important it is not the only factor in an open crumb. Finished dough temperature, proofing temperature, length of fermentation, number of stretch and folds all factors in an open crumb.
The issue I take with extreme hydration levels is its a single minded focus on the aesthetics of crumb. And that definitely comes at the expense of flavor, substance, and texture. High hydration levels will create a less flavorful bread, and a much softer texture.
While an open crumb may look lovely, bread is not holes with a few strands of gluten running through it. The obsession with gigantic holes in bread completely ignores the fundamental/essence of bread. When bread is nothing but holes there is no bread to eat.
I will use a 100% hydration preferment, but, I personally would not make a bread with 100% hydration.
