Even premade v premade I've found people can live through the quad DHC setup because at the end of the day the damage is still coming in piecemeal. It's much harder for a healer to have the Twitch necessary to help someone survive 3 6k Torpedoes (average damage. Realistically one of those is going to crit for 15k or more if they are fired properly).
Ive found this to be the case too now, especially with extra passives and all my crits working against me. my 4 DHC setups are currently parked, and im ether HY omega torp bombing or BO3ing. to many times now ive almost killed folks with 4 DHCs, just to not quite finish them off. if i had had ether a torp or beam closer it would have made a difference and gotten a kill