User blog comment:The Milkman/Reaper Logic/@comment-1900300-20120424000736/@comment-5124423-20120521170853

To save new 'fresh' organic life. The Protheans would have dominated all lifeforms in the galaxy. And if only one of those dominated species started a rebellion, the Protheans would have extinguished them. The organics have become a menace to themselves. The Reapers want to store the life like a LIBRARY or an ARCHIVE. Evolution showed that life has a beginning and end. With the Reapers' intervention, there is a beginning but no end because the species continue living in 'stored' form. And the Protheans would never have stopped developing better AIs and synthetics, so eventually, they could have created synthetics that were strong than any organic and would have overthrown their creators. Since the Prothean suppressed all other species in the Milky Way Galaxy, there would have been no one more advanced than them. Briefly, there would have been no organic being able to stop the synthetics from wiping out all organic life in the galaxy. The Repears prevent that from happening by harvesting the Protheans. With the advanced Prothean civilization gone, there would have been nobody to create any synthetics. And the 'not-so-advanced' species could have lived to grow until their time has come.