ASDIC managed the submarine threat rather than eliminating it

The distinction is between managing a threat and solving it permanently. Britain had invested heavily in anti-submarine warfare because convoy protection and the losses of Aboukir, Cressy, and Hogue made the problem impossible to ignore. Yet the Royal Navy continued building submarines of its own, which undercuts claims that ASDIC had rendered them obsolete. One British answer to detection was to make submarines smoother, quieter, and more streamlined underwater. The Admiralty appears to have expected countermeasures and understood that no single technology could end the continuing contest between submarines and anti-submarine forces.