I'm in the corporate world, I'm a hiring manager. I refuse to have a linkedin. Everyone says they wish they could do the same - then do it. Do the same. Nothing happened to me, nothing will happen to you other than your life being better because you aren't on Linkedin.
That seems so weird. Linked in is simply a way to connect with co-workers so you can contact them when you're no longer at the same job. I don't have them in my Facebook, I didn't have them in my phone, but if I want to contact them for connections or anything, LinkedIn is the place for that. How much you interact with the posting garbage is entirely up to you. I do it extremely little and I have no problem with LinkedIn.
I provide my phone number and email to coworkers that I want to connect with when they leave a job. Linkedin is corporate hustle poison and I refuse to be part of it.
I only use linked in every few years when I job hop. Literally the only reason I refuse to get rid of it entirely is that I doubled my salary the time I got a job.