Other companies tried the more or less just a Rolodex thing. The thing is that they still had the same incentives to try to expand your network.
But LinkedIn is basically fine as a way of keeping track of people and potentially contacting those you're not directly connected to elsewhere. I go through my connect requests once a month or so and ignore about half of them. I ignore any messages trying to sell me something or recruiters that are pitching something that's not remotely my thing. (In all fairness, my profile isn't really filled out so it would be hard to know what I actually do or have done.)
I do similarly with respect to notifications which is a good rule of thumb in general.
