User blog comment:Matthew Paul/BioWare never made a case?/@comment-3046679-20130110160425/@comment-24174486-20130111034555

Based on your choice during Rannoch, a synthetic race might drive their creators to near-extinction—exactly the sort of thing that the Catalyst sought to prevent, and had Shepard not delayed the Reaper invasion, this possibility would have never had the chance to unfold.

The Catalyst's reasons for creating the Reapers play a major role in the ending, but are they the focus of the ending? Not if you don't agree with the Catalyst.

It would be just like saying that if the Reapers were created solely to kill everything and the creator asked if you wanted to stop the Reapers or let them continue killing everything, the focus of the ending would then be killing everything.