Obviously someone hasn't played the game long enough to know that the detection icon used to be an optional captain skill one had to select. Everyone selected it because without it, the game was 100x harder. Without the skill, it put you at a serious disadvantage and it made playing against anything with a better detection rating a real PIA.
Imagine being stalked by a DD 6-7 KM away and you had no idea it was there. Then they would hit you with torps that had the detection rating of the current deep water torps (possibly better) out of the blue. One had to literally sail in a dramatic zig zag all.the.time.
It was not fun going from full health to dead from something you didn't have any clue was detecting you. There was zero chance of counter play.
bdnorcal