I think that's geared more towards situations when you have hosted layers on your account that change (at least that's what their video demonstrates). I didn't get the impression that this was a tool to repair items within a webmap. In my situation, I've added a layer to my map (through AGOL's Find Layers search interface) that is no longer publicly available.
I would be dumbfounded if this is actually an oversight on ESRI's part. I mean, *NOBODY* out there has had 3rd party data links break in their web apps?