Re: 618MB later...
I'm hoping for a change in social norms such that sharing address books with third party services begins to be widely recognized and condemned as the antisocial act that it really is.
With the benefit of hindsight, no arguments there. They seem to have changed the mechanisms around this, so I cannot see the specific boilerplate around the upload. I clearly wouldn't have used it had there been any suggestion the data would be retained beyond the immediate operation, but I still make no excuses for my naivete.
Out of interest, I note there is a Facebook function Remove all imported contacts which I would hope does as it says on the tin rather than spam the poor buggers with fake news. No idea if that's been around a while or only since this scandal blew up. Update: needless to say, it didn't actually remove all imported contacts at all. Still naive.