LinkedIn superconnectors are people who have connected to very many people, including people they don't know personally, to enable themselves and the people to whom they are connected to be able to reach a large number of people through "trusted connections".
With the introduction of LinkedIn's new InMail feature, anyone can reach anyone as long as they are willing to buy access to do so.
Since introductions via trusted connections are free, you may wonder, why not connect to as many superconnectors as possible? What's the downside?
Here's one drawback: If you have a very strong trusted network to a person three degrees out, and you connect to a superconnector who is directly connected to your target, then you've lost your strong connection path to the target. This is because LinkedIn will only give you the option to send an introduction to your target via the shortest path, in this case two degrees via the superconnector.
For example, say you want to connect with someone about a new business venture, and you find the perfect person to whom you'd like to make a pitch.
If your target is a third degree connection, then you'll send your introduction request to your first degree connection. Your first degree connection an add comments such as "I've known the person initiating this request for 20 years, and have known him to always work deals in that are fair, ethical, and profitable for all involved." Your first degree connection will then forward your introduction to his or her connection who is your second degree connection. Your second degree connection could add comments to the introduction such as "I've known the person who forwarded this introduction to me for five years, and trust her judgment that the person initiating the request is someone worth talking to."
Contrast the above scenario with an introduction from a superconnector. What could it say? Something like: "Please consider the attached introduction."
So a person receiving an introduction via a strong trusted network will probably be more likely to accept an introduction with favorable comments than an introduction with little or no comments.
If LinkedIn offered the option to choose among any path to a particular target regardless of whether the path required two or three degrees to get there, this would give you more flexibility to choose stronger connections. However, it may not be in LinkedIn's interest to offer such a feature. LinkedIn promotes connecting to only to people you know very well and trust. By removing a drawback of connecting to a superconnector, there is less incentive to not connect to people who you don't know well and trust.