If you are going to use it for a job hunt, then use it aggressively. Message/cold-call people that you want to work for, send them a cover letter and CV, ask to talk off LI and on the phone/over-coffee asap. Cold-emailing people from a company directory is kinda the same thing here. The 'rules' for Tinder aren't that far off for LI, sad as that is.
Outside of a job hunt that you're preforming, yeah, it's mostly recruiter spam. The feed is practically useless in my experience, but I am not a power user.
All that said, networking is that key to getting hired.