The most surprising thing is that there's people who think LinkedIn used to be good. It was built by spamming people and grabbing contact books without consent. It's always been trash.
I’ll be forever grateful to LinkedIn and I would never be in the situation I am right now if it hadn’t have been for it.
I only look at it once every couple of months to check up on old colleagues. If I am looking for a job I am forced to use it more often, but mostly just the messaging part. The feed is something I think most people can safely ignore.
"I only ever accept connection requests from people I 100% know to be honest, smart and good judges of character. That way, if I meet some new person, I look them up and see they are connected to someone I know: I immediately call the shared connection and ask their opinion."
In that sense, I think it worked as intended: people would only need to react to recruiting mail, and that only during the spans they cared about moving careers.
The whole "tell your life on linkedin !" promotion pushed by Microsoft clearly degraded that part.
My last role was gained by reaching out to a colleague I haven't talked to since college and asking about the role I applied to, and he was nice enough to give me a referral (I honestly wasn't expecting a referral. it was easily 5+ years since we last interacted, didn't talk that much in college, and I wasn't the best student to begin with). I doubt he posted his roles on Facebook so I never would have thought to contact him otherwise.