> Like we administered x mg of sulfer to the patient and they saw y outcome while patients not receiving sufler saw z outcome. When we stopped administering sulfer all patients saw z outcome seems to be isolating sulfer as causing y.
There is a reason we use placebos for control groups.
I'm more interested in the reason the OP had in mind. I don't think it's required that you have a placebo control group, but the OP might have a reason in mind that's something I haven't considered.
Uh, there's no requirement to use placebos or a control group.
For example, covid just uses a treatment group and considers the rest of the world as control.
Can you explain the reason?