User blog comment:The Milkman/Mass Effect in Retrospect/@comment-173.189.226.12-20130418023302/@comment-5267262-20130418133641

The reapers saving organics bit is basically the way they ignore 'young' species whereas other synthetics that go on a 'lets kill all organics' rampage would not. Think of the cycle as like a deer cull but instead of saving them from all the problems of overpopulation, it is stopping them from reaching the point of creating something that might (and from what the leviathans and the catalyst say they so, pretty much all of them did eventually) try to kill everything... ever.