One huge problem identified at the Tavistock was the lack of record-keeping and follow-up. At an earlier stage these treatments were justified on the grounds of research, but there was no control group and no proper protocol. No systematic data-gathering operation was mounted, and no systematic protocol of follow-up examinations. Instead, at some point the treatments were simply held to be a success and they carried right on.
So research opportunities that might have answered a lot of questions were lost. Nobody was looking at desistance or detransition rates or even regret. There was a huge attrition rate among the original participants, and nobody tried to follow these patients up to find out why. It was simply assumed that the patients who continued to attend were typical of the entire cohort. However, many detransitioners who have come forward have said that they didn't go near their original provider once they realised the whole thing was a horrific mistake, for various reasons.
The attitude even among medical professionals seems to have been, we know this is the best way to treat paediatric gender dysphoria and that's what we're going to do. Anyone who treats a child in a different way (as would be necessary for a control group on the watchful waiting pathway) is a child abuser, and anyone who questions our actions is a bigoted transphobe.