If I tried to arrest my descent by fin strokes I would crash into to the bottom or continue past the planned depth (on a wall). By the time I get down to, say, 25m my neoprene drysuit will have lost around 4kg of lift, add in the 3,600Lt of gas I carry and finning isn’t going to work. I add gas to the suit as needed all the way down, then add more as I approach the planned depth to stop gently.I get that, and I understand the principal behind it.
My understanding was that while some air would need to be added at depth to maintain buoyancy, you should never be so over weight that the air is required to arrest the descent vs using kicks to arrest the descent and then air in the BCD to reduce the work of staying at the desired depth.
Edit: The descent is done slightly head down so finning would only send me deeper. Your suggestion requires a diver to be vertical, i.e. head up.