I have often wondered why it is "on" by default. It catches a lot of people out.
Broadcast waves carry a timestamp to say where on the timeline they belong. This can be very useful if, e.g. you're sharing stems with someone else, so all your tracks line up, or in video/radio, where everything has to be in sync.
I guess my question would be, why are the files timestamped way into a project? Someone more knowledgeable might chime in with an answer.
Glad you got it sorted, anyway.