Yes but you are comparing a present orange to a future apple. When the ditch failed and eroded through in the same or an adjacent place it would have transported much more sediment downstream.
I wasn't on site - I don't know a lot of specifics about this site. But doing nothing to a road for 15 years (Matt's statistic) is not a good option from a geotechnical standpoint. At that point it often costs as much to play catchup with maintenance as it does to build the road in the first place, and only a fraction of that to put it to bed. For most of these roads, unless there is some assured annual funding source, deactivation is the only practical option - and it often has to be quite thorough. The road up from Squamish to Mt Habrich is a great example.
It's not like this is some overhanging sport crag where you might be worried that the hiking approach will make your legs too big and heavy, right?