I guess it depends in which domain you work?
In system programming, "clock_gettime" gives you nanoseconds. If you work with GPS timestamps, you have nanoseconds.
Could it be that JS's Date doesn't support nanoseconds because it cannot represent them, which is the issue we are talking about here?
Don't get me wrong, I understand this is not something that everyone uses every day, but to me it's a pretty straightforward example that can happen in a wide range of situations. It certainly happened to me/colleagues several times in several companies.