Aah, Tourist, I see what you were getting at.
Amen, Deacon!
With that in mind, you can get a "mission" kill rather than a "hard kill" depending upon depth, aspect, and how well maintained a sub is at greater range, but given the size of the area underconsideration (20-30 miles across) you still need to localize a target before you were to consider that little bucket, were one available.
The assertion that such a weapon removes from play target localization was, as you note, risible.
Jack: thanks for that as well.