Adding Allied Submarines to a mission. Why is it worthless ?

I thought that adding additional submarines like a wolfpack along with User Controlled subs, that the wolfpack subs would at least use their deckguns. I think in general they are worthless and just sit there doing nothing but acting as decoys. They don't even sink.

So, using more than one submarine is a waste of time. Right ?

Regards
Jib01