On a monthly basis, I get LinkedIn "invites" from friends who simply didn't understand LinkedIn's hostile and deceptive user interface. They think they're just importing their contacts to conveniently++ find existing profiles but in reality, they're unwittingly giving permission to LinkenIn to spam their address book to recruit new members.
You may be good at defensive web surfing to keep your contacts private but most others are not.
Btw, there was a previous discussion from Feb 2014 about it: https://news.ycombinator.com/item?id=7276032
[1]https://medium.com/@danrschlosser/linkedin-dark-patterns-3ae...
++ (understandably because they don't want to manually retype each contact name into Linkedin. Ain't nobody got time for that.)
I wonder if you can prevent them from stealing the address book if you install their Android app?
If gmail started emailing your friends because you used gmail, that would be a good reason to not use gmail.
You seem to be a little out of touch here. There are several examples of people withholding their contacts list from services like LinkedIn right here in this thread. It's not hard to imagine at all -- just read the posts.
In fact, right above your post that you responded to, the hn user vitd wrote, "why did you give them your contacts? I've been on it for years and have never uploaded a single contact."
Lastly, you're trivializing the situation by suggesting that recipients just mark it as spam and move on. The issue is that LinkedIn deliberately crafted the emails with header "FROM: YOU" and your photo in the message body to make it look like you explicitly sent the email inviting them to join. It's clever social engineering so that the recipients harvested from your contacts list do not treat it as spam. Some recipients know the disguised nature of LinkedIn spam and know you didn't actually send it but many do not (especially older executives). In those cases, they think that you are one of those clueless flakes that signs people up for multi-level-marketing vitamins and vacation timeshares. People genuinely got embarrassed by LinkedIn's spam practices.
Enough people were angry about spam being sent behind their back that they sued LinkedIn: http://www.businessinsider.com/linkedin-settles-class-action...