It really isn't hard to build PYMK. It's basically just triangle closing on common friends and address book import.
I find it very convenient to have offers come-in out of the blue, only having to pay the cost of tweaking my profile once a year, and occasionally skimming/deleting random recruiter messages.
I see it as being open to opportunities. Usually, I would only look for a job when: 1) Unemployed, or 2) Unsatisfied at my current position. In both cases I would be motivated to solve the problem ASAP.
But being approached when happily employed gives you the upper hand during negotiations, allowing you to make demands that you would usually not be so confident to make. Not to mention becoming aware of good opportunities when your "job radar" is turned off.
Without LinkedIn I would never have gotten the offer, because my new employer would have had no chance of knowing that I no longer work for one of their customers.
But who thinks of LI as general purpose social media? I don't think anybody uses LI except in the strict context of finding new jobs, and making sure you can find new jobs in the future.
I don't get the criticism. It's like blaming the screwdriver for not being able to hammer in a nail.
It's a jobs site. And for that purpose it's pretty good. End of story.
I also use it as an up to date electronic rolodex of sorts. Is this person still working at Cisco? What's their current contact info? Let me LinkIn with you so I don't need to keep this business card, etc.
"10 years ago I was a alcoholic leprechaun but today I finally got that job working as a chimney sweep"
"Here's a picture of me with a homeless person I spoke to on my way to work today. It turns out they are people too."
"Don't you just love our military personnel/democracy/babies? One like to show you love these things. One share to show you don't hate them."
"Here's a pointless meme about mindfullness"
"Hey look at my dog wearing a santa costume" (actually that would be kind of cool)