What he's saying is that the Japanese were stupid in their use of submarines.
Germans weren’t. We stole some ideas from them. Early in WWII, we didn’t do unrestricted warfare. Then things changed. Our torpedos sucked early on too. The Japanese long lance torpedo was very good. Not all the boats were commanded by captains that would fight the boat in a tough way. The second gen Captains like Morton, O’Kane and others soon took the reins. The USS Cavalla sunk the carrier Suikaku in June of ‘44, fired 6 torpedoes and 3 hit. A legend was born. We had a fast attack boat carry on the name. I had a good friend on it. I toured the U-505 in Chicago as a kid. You’re right, totally cramped. The German U-boats were more cramped than ours and played Billy-hell in the North Atlantic. They kind of invented unrestricted submarine warfare. Our boats took it up to the next level. Now our FBM’s hide out and wait to destroy a country and our attack boats hunt something to kill, just like everybody else, underway underwater.