Bottleneck is a useful and picturesque metaphor to denote the point of constriction of something that ought to be flowing freely:
Even if the manufacturers could obtain ample raw material, the shortage of skilled labour would constitute a bottleneck in production.
The metaphor is not new, but it has recently had a sharp rise in popularity, perhaps because our economy has been so full of bottlenecks. It needs to be handled carefully in order to avoid absurdity: it is necessary to remember that the most troublesome bottleneck is not the biggest but the smallest.