Earlier quoted context omitted.
The human raters are used to assess the performance of the algorithms (i.e. do human opinions align with algorithmic ones), not to rank content directly. A recurring theme with Google is that they always want to solve problems algorithmically.
And what do they do with these human assessments then? Of course they feed them back to the algorithm so that it can improve. In effect it is still humans influencing the search rankings albeit indirectly. So it is a bit duplicitous to say that "it is the algorithm that decides" when there are humans providing learning data for it.
It's more of a check step. So, for example, if humans think one website is vastly more (or less) authoritative than human raters, the engineers might dig in to see which aspects are causing the algorithm to evaluate it differently and, potentially, test tweaking the algorithm accordingly.