I thought that that scene made it pretty clear that this was an "everyone here can do this" thing that we were just being taught how to use properly use for once. She did say that this was how they preserve history and I assume she wasn't just talking about herself. Just a part of the original powers that the Echo stems from.
In any case, it negates everything that comes after because if you lose a memory, seems like it'd be damn easy to get that back by walking a few feet and activating your brain but...I'm just looking at the story too closely like Yoshi-P said, I guess. My bad for expecting basic logic in said story.
