There’s a difference in cat-backing and in pulling/bending round-backed intentionally and knowingly when you’ve developed the strength to handle it. Strength is not only an adaptation of the muscles and nervous system, remember. Connective tissues have to adapt as well. Just as an experienced powerlifter can handle 1RM squat weights without injury, it’s just as possible that experienced strength athletes will adapt both anatomically and technically to a round-backed style of pulling/bending.
If youre a newbie at these lifts, rounding is def not a good idea because you need to strengthen the connective tissues to handle the load before attempting to round. Most people will be stronger in the musculature than in the connective tissue during a rounded lift so the injury potential is higher. When you see advanced lifters round in the DL or GM consistently, theyve adapted to it. By developing the isometric strength of the trunk muscles, postural stability of the lumbar spine can be maintained even in flexion. The hips and other related muscles are actually handling the loads, while the spine itself remains stable. As long as the spine power is low, then the risk of injury is low.