It's not like the issue they're dealing with doesn't exist with literally every clock in the world - it's just that we didn't have a clock that was sensitive enough to notice before.

In a sense, this is not a property of the clocks, but rather just the way nature is. We can't keep these clocks in sync at various places around the world, because the thing they measure is not in sync at various places around the world. But, we've known that for about one hundred years - what's the big deal?

nullc is right, this is a bad article.