It's a time thing rather than a memory issue.
It can't time something that hasn't happened. If it allowed you to sit and wait for everyone to finish, then you would get times for them, but do you want to sit and wait for ~8 minutes after you've finished your race, while the guy in last place (that you were just about to lap) makes his way round the Nordschleife?
That's why you can chose when the race finishes in the lobby, so that everyone in the lobby gets a finishing time.