Well, in practice the latency that normaly matters is between "start doing activity" and "finish doing activity", and the time actualy working (that depends on bandwidth) is normaly orders of magnitude bigger than the time waiting for data (that depends on latency). There are exceptions, but not many.

And now that I really thought about it, looks like the article's law isn't that relevant in practice. Yes, you can always trade latency for bandwidth if you throw some money at it. But money is finite.