I don't have a problem at all? All my data has been erased from my phone while doing a normal software update, following normal instructions. Even if I get everything back from a backup, it's not what you expect when doing a software update and takes time.
And indeed, I had no clue whatsoever what happened and why, hence I'm not sure what directions to give or what exact help to ask for.
So even if "millions of people" successfully updated their phone, I find that an inappropriate / arrogant remark to someone who just had to erase his phone for no clear reason and comes here looking for help (in a very polite, non-insulting way).