LinkedIn displays the number of connections a user has very prominently on their profile, in the top card on the page.
However, once a user has over 500 connections, it switches from a specific number to an unspecific number, and shows '500+' instead.
It has two goals/benefits; it clearly separates those who have reached 500 from everyone who has not, and makes sure the quality of connections stays high. It's a mixture of prestige (you have a well developed social circle) and functionality; it becomes more and more likely people unknown to you are at least a 2nd or 3rd connection. So, 500+ group is like a badge and you are very visible.
Specifically adding how many contacts you have becomes redundant after you reach a certain number. LinkedIn is not like Facebook that knowing a lot of people makes you seem more popular. LinkedIn is supposed to be about the quality of connections. Showing an exact number encourages hoarding (sometimes even meaningless) contacts, which is not a goal LinkedIn strives for. Keeping the displayed number cap at 500 encourages people to go out and connect, but not to the extend that they will connect to anyone.
So in short, it's a decision based on business goals.
Actually they used to show the exact number; however this resulted in people comparing (and really, competing) their profiles solely based on this number, no matter what those connections were really like. Some sites, like TopLinked, even created public leaderboards to showcase profiles with the highest amount of contacts – and offered a $10/month service to help you boost that number...
Obviously, LinkedIn didn't like this. As Chris Nodder writes in his book, Evil by Design:
This again appealed to users' competitive nature but was completely counter to LinkedIn's mission to create a "professional network of trusted contacts." LinkedIn claims that "Connecting to someone on LinkedIn implies that you know them well" and that makes business sense. LinkedIn makes its money from analyzing the connected nature of individuals to determine their traits and target advertising. If the connections are random, there is no money to be made. It also makes money from upselling users on premium features such as wider searches (beyond third-level connections) and the ability to send "InMails" to people outside their network. Again, if an individual has a massive network, this reduces the need for these services. Steven Burda, a highly linked individual, claims he can reach 97 percent of LinkedIn members via his third-level connections.
When LinkedIn changed users' profiles to show a generic label of "500+ Connections" rather than a true figure, TopLinked could no longer maintain its leader board.
So there you have it – they do this to guard themselves and their users against services looking to exploit competitive nature and pride.
