I'm sorry, but I can't keep silent about this. I still reckon that the whole concept of the Time Crack in Series 5 is totally ridiculous. Nothing about it makes the least bit of sense. We're told that things that get absorbed by it are written out of time and thus never existed.....but everything that said things did and caused still happens, when there's no way it could have if they never existed in the first place.
Then there's the horribly contrived way it's used to retcon events from past shows out of continuity. The Dalek invasion now never happened, because the Daleks fell into a Time Crack. The Cybermen in Victorian London now never happened, because they fell into a Time Crack. Why don't the writers just say that all of the Classic series and Series 1 to 4 of NuWho fell into the Crack, as they obviously don't have much regard for what's gone before!
Then there's the horribly contrived way it's used to retcon events from past shows out of continuity. The Dalek invasion now never happened, because the Daleks fell into a Time Crack. The Cybermen in Victorian London now never happened, because they fell into a Time Crack. Why don't the writers just say that all of the Classic series and Series 1 to 4 of NuWho fell into the Crack, as they obviously don't have much regard for what's gone before!