Huh. It seems I'm the only one here who finds value in LinkedIn. Yes, it has led to actual, paying jobs. It takes some management on my part, but it's a lot easier than hunting around from site to site, or going to meetups, or any of that other stuff. Do I get spammed? Sure. That's why I have a specific email account for them. Some of the spam is quite informative. I learn about openings early on, and can often find…
I don't get the hate either. When it comes time for your next job search, it's incredibly valuable to have a consolidated list of everyone you've ever worked with where you can see where they work now. When I was looking for some part time work while launching my (bootstrapped) startup, I reached out to about 50 people from my LinkedIn network and it worked out great for me.
As for spam, I just filter and/or ignore it (yes, I get a ton of it, maybe 10+ recruiter emails a day).