Its to do with FRMS and Crew members responsibilities. If you live more than 90 minutes away from your base you have to make alternative arrangements either at your base or in this case from where you commute. Historically Airlines and crewmembers avoided the commuting subject. Some UK AOC's moved on the subject as they started to introduce FRMS.
Here's an easy question: if a crew member lives within 90 minutes from his home base and reports at 2359 and you live 90 mins away from your commuting base and then jumpseat in and then presumably do some hanging around whose the most tired?
That should hopefully answer the question