First off, I will point out: this is not a leak of your contact list, it is a leak of your calendar. You might have a very different perspective of the kind of information you store in your calendar, as it includes (explicitly from the article) meeting notes (in which I can imagine someone even having stored a bunch of sensitive corporate information) and the date/time and location of your upcoming whereabouts.
That said, I will also attempt to answer your question as asked, partly as everyone else is responding to you under the guise "LinkedIn should not get this data", yet, I, generally agree with you: for most people that is the worry of someone who is paranoid. That said, I /can/ come up with legitimate (but unlikely) situations where I'd fear for someone's life based on an address book being accessible from LinkedIn.
However, to me the key problem here is "in plain text": it is one thing for a service that already knows too much about me and the people I work with to know a little more about them, or think about people hacking into LinkedIn (again unlikely), but it is an entirely different thing for everyone sharing the WiFi network I'm on to have my entire contact list: these are people who are actually in a position to take action.
It might be your ex-husband who has been stalking you ever since the divorce, or it might be the creepy guy that hangs out at the comic book shop who seems to have taken slightly too much of an interest in you. It could even be someone running a scam: they go to conferences, intercept as many address books as possible, and try to use the result for some kind of social engineering hack or even identity theft.
If you haven't yet, I thereby implore you to consider "what could I learn about my best friend if I had their entire contact list": looking at it from the vaguely mischievous and voyeuristic stance of it being someone else's data might make it simpler to envision why that person might not want you to know all of that information. If that fails, then try to think about it from the perspective of a thief or an evil employer.
That said, I will also attempt to answer your question as asked, partly as everyone else is responding to you under the guise "LinkedIn should not get this data", yet, I, generally agree with you: for most people that is the worry of someone who is paranoid. That said, I /can/ come up with legitimate (but unlikely) situations where I'd fear for someone's life based on an address book being accessible from LinkedIn.
However, to me the key problem here is "in plain text": it is one thing for a service that already knows too much about me and the people I work with to know a little more about them, or think about people hacking into LinkedIn (again unlikely), but it is an entirely different thing for everyone sharing the WiFi network I'm on to have my entire contact list: these are people who are actually in a position to take action.
It might be your ex-husband who has been stalking you ever since the divorce, or it might be the creepy guy that hangs out at the comic book shop who seems to have taken slightly too much of an interest in you. It could even be someone running a scam: they go to conferences, intercept as many address books as possible, and try to use the result for some kind of social engineering hack or even identity theft.
If you haven't yet, I thereby implore you to consider "what could I learn about my best friend if I had their entire contact list": looking at it from the vaguely mischievous and voyeuristic stance of it being someone else's data might make it simpler to envision why that person might not want you to know all of that information. If that fails, then try to think about it from the perspective of a thief or an evil employer.