Thanks, I have come across this in the past. The basic assumption is that the created_at/updated_at timestamps mean the time the event happened, when in fact they are the times that the event was recorded. A subtle but important difference. When dealing with the real world we need the times of the real events, not the time the event was recorded. Unless of course we are investigating the database.
The most glaring difference would be on a user record; date_of_birth vs created_at.