Universal Genocide

After a certain point, universes created by time travel were automatically sterilized of those who could oppose time traveling criminals; alien life, political enemies, those who advanced science / knowledge / culture. Sometimes the nearly innumerable robots that were available sterilized universes of all life, leaving them to be seeded with kidnap victims, or grown life-forms, leading to The Great And Bountiful Human Empire. Other times, data (including organic memories) editing completely removed those who were immediately killed, and thereby spread word that the time traveling criminals desired their destruction.

See: All Real Write-Off