Serious? About the fins or the feet flatening?
Full foot fins ARE a more efficient design. The fact that there are so many full foot semi-toys does not change that reality. What do deep water free divers use? Open heel fins have practical benefits, including easy use of boots for warmth or walking on difficult surfaces, and ease of removal, but for sheer in-water efficiency they are not as good as equivalent full foot pocket fins. Most divers are never exposed to anything other than open heel fins. Too bad.
Full foot fins ARE a more efficient design. The fact that there are so many full foot semi-toys does not change that reality. What do deep water free divers use? Open heel fins have practical benefits, including easy use of boots for warmth or walking on difficult surfaces, and ease of removal, but for sheer in-water efficiency they are not as good as equivalent full foot pocket fins. Most divers are never exposed to anything other than open heel fins. Too bad.