Cass CAN NOT say that puberty blockers have no benefit. In the same way that Cass CAN NOT say there is a benefit.
Why? Because there is no evidence based for either position.
Cass CAN say there are significant harms that puberty blockers produce. Cos the IS evidence for this. Therefore there's no ethical base for encouraging their use.
You have to have an evidence based to say that there is a significant effect benefit to out weigh the harm. But you can't unethically seek to build this evidence either.
We also know the placebo effect may be at play, at least in the short term.
The absence of long term follow ups is one of the critical issues here. As is the ability to identify cases where other issues are driving problems and that it's not about gender identity.
Further research may well find that evidence in either direction to either say it's utterly harmful or have enough benefit to some children to make it worthwhile.
But you also can't harm lots of other children in the process of helping a tiny number - no one should be collateral damage for someone else - even if you do find evidence of benefit for some. Until you can find the ' true trans' magic formula, you cant risk the lives of other children.
Cos ethics and evidence based medicine.