In a SmallWorld, weak links are those which are not heavily trafficked, but connect disperate clusters. As such they can be very useful.

For example, many people hear about oportunities such as jobs, places to rent, people to date etc. via weak links. Why? Because the strong links are the people you see every-day. They're part of your world, what they know, you know already. Why you don't, they don't.

But the weak links, the person you studied with 10 years ago and see once a year, they are gateways to unknown spaces.

Same in wiki of course. Many of the "see also" links at the bottom of pages link to others in a dense cluster. But the ones that lead out of the cluster are often the most inspiring of new ideas and connections. (Compare WikiIsPayingOff)