When i think of the roots i think of how similar they are to the leaves, and we prune the leaves. They both carry water and nutrients, and occasionally they both grow out of control or just need a trim. So many of us use fabric pots or air pots and they all air prune the roots, I've even had to sever roots that grew out of the smart pots. But in regards to hydroponics I imagine you would do more cuttings of roots than letting them dry and i think this is a good thing. Everytime we cut a root it grows more of the little tiny branching roots or fibrous roots in its place, and these new tiny roots are much better at nutrient intake. My guess is because they're young, healthy and undamaged. I don't grow hydroponically but if i did i would definitely be root pruning, just as safely as i could and without getting too close to the heart of the plant or root ball or whatever you like to call it. 😊✌️ Happy growing your plants look very beautiful and healthy, I'm always a bit envious of the people brave enough to do hydro. Happy new year