First off, I will say that I am not a materials scientist, but just using normal logic and basic physics here. I could be completely wrong but not sure that I am. I would be interested in other's thoughts one way or another.
I'm sitting at my desk working so don't have much to demonstrate this visually, but this might do it. There is a cord wrapped over an iPhone, which is a small radius, but still probably as think as many standard recovery points:
Imagine its a rope and there is 8000 lbs of force pulling it over hardened steel. Obviously the fibers will stretch, but they won't stretch evenly (more on the fibers on the outer edge) and they won't compress evenly (more on the fibers on the inner edge). Think about this picture, but with a 1/2" rope rather than a tiny cord and hardened steel rather than a phone. Lots of stretching and compressing, and most importantly, friction.
on the other hand:
With a larger radius, the compression and stretching forces are more evenly distributed through the rope and there is less friction at load.
Again, I may be thinking all wrong about this, but look at these two products. The first is a MaxTrax hitch point made specifically for soft shackles. Look how large the radius is:
And here is the TT recover point rounded over, in theory to support soft shackles:
Just my opinion, but I would always use bow shackles on vehicle recovery points and save the soft shackles for connecting to tree savers or snatch straps and the like. A $12 dollar bow shackle will do that job all day every day for years and years. A soft shackle....not so much and probably not more than once.