User blog comment:GodzillaMaster/Truly Extinct?/@comment-1221773-20111118214259/@comment-1221773-20111119025242

You forget that the Collectors were disposable, mindless tools of the Reapers, not sapient, independent beings. The Reapers didn't care what happened to them, and they didn't need any extra "shelter", be it for living space or protection. The Collectors probably had as little need of individual living space as ants, and until Shepard's time, the Omega 4 Relay's IFF system was sufficient to eliminate any intruders.