1) Balk at its seeming absurdity
2) Assume linkedin is a rational company and take the seeming absurdity as an insight into how to convert free users into premium users.
It is shocking how little it takes to convince some people to pull out their credit cards and sign up for an annual subscription.
Every single step that has anything to do with not giving them money by the way is met with Captcha. I've never filled out so many captchas as when I tried to unsubscribe from Linkedin spam.
My only remaining option was to mark all email from them as spam. Stop using Linkedin. I certainly won't think fondly of anyone who tries to add me there. People just put my email address into a box and I get an email from Linkedin on top of the spam the company still sends me.