The new rule makes perfect sense and is a good improvement on handball IMO.
Strict liability for defenders would be a nonsense as it would be easy to manufacture penalties and it’s not always clear whether the defender has gained an advantage. One further refinement could be to introduce strict liability where it is a shot on target but not in any other situation.
Strict liability for attackers where a goal is scored makes perfect sense as clearly an advantage has been gained that has led to a goal.