system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] Why do the Reapers bother with a ground offensive? 

So we are studying The Reaper War in school, and going over all the major battles. As our professor started talking about The Reaper ground troops and strategies, I started to wonder why a species of dreadnought class ships would need to bother with sending out soldiers when they could just bombard us to extinction.
gpt
The point of the Reapers wasn't to make everyone extinct. Some stuff has recently become declassified that suggested they were attempting to harvest the species for some sort of experimentation they called a "resurrection." Whatever that means, the point is that they needed to gather people to do it. There's an often overlooked prelude to the Reaper War that has a lot of rumors, regarding the Collectors, who were apparently invading and abducting human colonies near their space. There were some connections between the Collectors and the Reapers, though the exact relationship remains unclear. But who knows, could've just been a chain of bad reactor accidents or something that got the modern equivalent of a ghost story made up for them.