DS is needed
In an average game of survivor you are most likely going to have a killer that will stay near or close by to a hook and will come for those two survivors, if the killer spots the injured survivor he will go for the injured survivor, without ds this can be frustrating especially if you are solo queue and you get unhooked right in front of the killer.
But lets say in other circumstances the killer is nice and goes for the rescuer instead, then the survivor will go get healed or work on gens in the mean time. Most of the time ds will run out in this time, but if the killer finds you again in this time you can still ds them.
I dont think ds needs any nerfs or buffs, the only understandable one would be to end ds when you work on a gen.
As a killer you can play around this, ds is meta and should be predictable.
---In conclusion I do think ds is stupid and its just another breeding perk for toxicity and unfun playstyles but it is needed in the environment of dbd in its current state sadly.----