I get a torrent of recruiter spam in my InMail but I also got my current job through InMail; the person that reached out to me was a team technical lead at a company you've heard of that I very much wanted to work for, and I took the bait, and nearly doubled my pay in the process

And I've never posted or paid. I just have a profile, and it's not even a very good one

So apparently there is some value