Well that was almost a decade ago and I'm unaware of Apple making similar mistakes recently, however I have never managed to figure out iTunes sync in the meant

Well that was almost a decade ago and I'm unaware of Apple making similar mistakes recently, however I have never managed to figure out iTunes sync in the meantime. However this behavior is really out of the line for MS since they've got a good track record on backwards compatibility and data preservation. Previously during in-situ upgrades the installer would back up gigabytes of data in a special folder on the off chance that they might be needed again in the event of a rollback, and somehow they managed to drop the ball this time round.