....it seems to substitute the findings of investigating police and prosecutors for those of a jury.
Isn't this the case with the majority of criminal proceedings. Law enforcement first ascertains the probability that a crime has been committed.
Police see a man climbing out of a broken store window and arrest him on suspicion of burglary vs they see a man two blocks away from a store with a broken window and don't arrest him. First man goes before the jury and second one does not.