One aspect of shooting with a loose grip( soft fingers) is that the bow, on release, is free to go where it wants to go, unhindered.Generally it will jump onto the sling. If you change your form anywhere in the bow arm, the bow will jump differently and you can detect those changes and do something about it.
If you have a tight grip, the bow hardly moves on release and the bow arm can interfere with the shot, without the bow showing much change in its reaction.
This morning I was helping an archer with his grip on the bow. He tended to grip the bow and pull it across to his right on release. There was no jumping of the bow as it was being held too tightly.
He struggled for a few shots to keep his fingers soft, but when he managed, the bow jumped to his sling. That in turn seemed to pull his whole bow arm towards the target as opposed to pulling across to the right. He could feel the difference between the two ways of holding the bow and could tell when he slipped back into gripping it.
With finger slings, some archers find the jumping of the bow makes their finger or thumb feel sore. I liked a finger sling but did find a soreness coming on. A wrist sling can be made so that it almost feels as if it isn't there. They are usually very easy to adjust for how much slack you have. Too much slack and the bow falls through the gap unless you grab the bow at the point of release.... NOT a good thing. Too little slack and the jump of the bow can be so confined that it isn't noticed. That isn't necessarily bad, but it can lead to gripping the bow even though using a sling. There is then no point in having one.