I can't say who i am,or who works for Bioware
The Dark Rift is a Plague that was killing all life in the Galaxy,stars suns planets,people (exception) Humans.
The plague was also killing off Reapers at a fast pace through Dark Space effecting their Organic forms,thus using a synthetic means to (Preserve) and harvest all life to stay alive....using Human DNA.
Thus in Mass Effect 2 using Collectors as a means to spread the virus to others leaving only humans to harvest as there was no means to save the other races because of nature selection.
The Reapers building the Mass Relay's was desperate,to week to travel by dark space alone, they built the Catylist and Citadel by Mass Relay travel and to preserve brain function.
The Drak Rift thought to Effect all Reapers,All for exept one like Dis.
The other Reapers tried to attack Dis to harvest him as seeing he was the only one to have had a DNA change by selection.And a conection to the Shepard.
And the only Organic Laviathan still able to travel through Dark Space without the need for Mass Relay's.
This September should be one hell of a ride.