What is the point of teaching someone to only dive with their hands folded across the chest, or in front of them? Put them in a streamline position when you are swimming forward, and when you are not swimming forward, it doesn't really matter much where you have them, so use them for whatever you want. Often this teaching of 'no hands' diving just leads to an obsessive compulsive use of inefficient diving fins and swimming techniques that are suboptimized for cave or wreck diving and inappropriate for the types of diving the students will actually be doing.
I am not sure I understand how discouraging the use of hands for
swimming leads to either situation.
Swimming underwater with hands / arms is far less efficient than
swimming with legs and fins - the muscle mass and power of the legs is simply much greater than that of the arms. (I even make a point of noting how silly Lloyd Bridges looked in Sea hunt, when he was swimming underwater with his hands.)
What do you see as the relationship between 'no hands' instruction and the use of inefficient diving fins? I don't get the connection, but I may be missing something.
I agree, that there is a time and place for the use of hands. If a diver is in a very strong current, they may want to use their hands to pull themselves along the bottom. That is far less tiring (and more efficient) than trying to
swim with hands / arms, and less tiring than trying to swim against a current with fin strokes alone. If there is a light current, and a diver wants to hold position on a wreck, they may want to put a finger tip on a surface to hold station. Teaching them to swim without using their hands does not preclude them from learning either of these techniques.
I tell OW students beginning with the first session in the pool, 'Keep your hands out of the equation.' I make it clear that they should be able to swim forward, maintain buoyancy, turn, back up, etc. without
any use of their hands whatsoever. Once they are able to do that, it is actually easier to teach them the proper use of hands for specific situations. Students instructed in this manner do not feel a need to use their hands for swimming, because they are facile in the use of their fins. I also tell students that, if they see another diver swimming with their hands, the chances are that diver was not given good instruction to begin with.
In teaching climbing (e.g. rock climbing), I tell new climbers that their hands are used for stabilization, and to supplement the use of their legs. Many climbers start out by thinking that they are going to pull themselves up a rock face with their arms, which really isn't going to happen in most situations. They use their (FAR more powerful) legs for upward thrust, and their hands become adjuncts, for fine tuning position. Just s in diving, it is not a matter of 'either-or'. It is a matter of using legs / feet and arms / hands according to the power and efficiency of each.