When I used to carry a 649 Bodyguard in a raincoat outer pocket, worn over a sport coat in cold/wet weather, I could easily have my hand on the gun without anyone realizing I was doing something other than keeping my hands warm. Much faster than trying to get at my primary weapon. Fortunately, I never had to perforate my raincoat pocket.You can stick a jframe size revolver in a jacket pocket, hoodie anything you can use cover garment and not have to pull it out to fire it. Think what an advantage that is.
Being able to surreptitiously grasp a pocket-holstered weapon is an advantage not typically available with other carry methods. Obviously, the constraints of the pocket mean even greater attention must be given to avoiding having your trigger finger be caused to enter the trigger guard or touch the trigger while drawing from the pocket, and especially while clearing the pocket mouth. This is also where the weight and length of trigger pull of a DA/DAO revolver's trigger might be an extra bit of prudence if things get fast and fuzzy.