Perhaps bad quarantine kills fish all the time, but a good one shouldn't. I don't see why "quarantine" immediately must mean "hit the fish with everything you've got at your disposal".QT kills a lot of fish. I hear it all the time.
As I am in Canada, and have no access to any medication beyond copper, I separate all incoming fishing into different holding tanks (or currently, a tupperware container for two of them). I'll typically treat with Humblefish's hybrid TTM with a hydrogen peroxide dip going in, and may or may not treat at further length with copper depending on the source of the fish.
For the OP: I typically throw in a bag of media (translation: bio-gems) from my displays into my QT, and always have ammonia badges ready. It's cheap and easy, and enough for one fish or two without having to worrying about adding nitrifying bottled bacteria.