Foxhounds for hog dogs, who runs them??

I keep seeing posts like i want a silent hound on this site a lot and i dont get it, a silent foxhound would have to almost be injured to be silent, is the deal is these newer breed of cur dogs dont have enuff nose to trail anything over 30 minutes or what is the deal?? Or is it they want a silent hound thinking it wont run off hogs when it opens or what is it??? If somebody had a good silent foxhound it be worthless, if it rolled out 1 mile and found a hog and then worked up the track for 30 minutes and went in the oppiste direction away from the hunter and other dogs how could any dog honor its open or even the hunter ever find the dog if it was not giving mouth??? I must be missing something??? Do they mean silent until jumped or do they mean silent until bayed??