No, because if there were a treatment as safe and effective as chemotherapy at treating cancer, but that didn't cause nausea or vomiting, we'd all switch to it in a heartbeat.
By that token, what specifically is the clinical benefit to the vomit stage of chemo?
The argument is that the vomiting is a necessary step of this powerful medicine, and that the medicine is curing mental disease.
I'm not defending ayahuasca, I actually do think it's a sketchy corner of the psychedelic world to be trodden on very carefully, if at all. Just trying to supply the perspective.
"What disease is ayahuasca fighting off? And specifically what is the the clinical benefit of the vomit stage?"
I have heard people describe ayahuasca purging as getting rid of mental and/or physical toxins... as getting rid of depression, emotional/psychological baggage, medical maladies, etc..