I had a similar experience. In 2014 I reported an issue where you could take over someone's account by adding an email you control to it and having them complete the flow by sending them a link (which, unless they looked very carefully, looked exactly like the regular log-in flow at the time - especially if they used a public email service and you registered a similar-looking account).
I tried it on a friend and it worked, but LinkedIn's response was basically "meh".
My life has only gotten better since I deleted LinkedIn a few years ago. I know I'm in a privileged position to be able to do that, but I strongly recommend everyone here consider whether what they gain from their account is worth the crap and spam they have to put up with.
LI is terrible if you actually try to use it, but it's harmless enough if you just use it as a profile hosting service, where people are likely to look. I just auto-archive their emails and only visit the site a couple of times per year.
I tried it on a friend and it worked, but LinkedIn's response was basically "meh".
My life has only gotten better since I deleted LinkedIn a few years ago. I know I'm in a privileged position to be able to do that, but I strongly recommend everyone here consider whether what they gain from their account is worth the crap and spam they have to put up with.