There seems little upside between what this paper proposes and everybody just sending all data to all stakeholders of figure 1. The blockchain itself does not conserve confidentiality of placebo placements outside of this process and "Regulatory agency" and "Data safety monitoring board" are presumably two trusted parties that could, post hoc, compare their two databases and draw the same conclusions.

Adding a semi-public blockchain seems like a neat little tidbit but it mostly adds a formalization of the process (which would of course be a good thing) and buzzword-worthiness, thus warranting the "wasteful" label.

> permissioned blockchain [...] for very little money Is that a solved problem yet?