They used to give guidance about what 'know' meant and I still adhere to the 'I will only link with you if I have properly worked with you' line. The fact that few other people do have devalued its use.
At some point, LinkedIn changed its mind and decided that you should connect to anyone you're barely acquainted with and/or have exchanged an email with. They're actively encouraging forming these "devalued" links. They even use shady practices like borderline forgery of invitations.
> LinkedIn changed its mind and decided that you should connect to anyone you're barely acquainted with
This was all in the interest of keeping the numbers going up which is obvious. And that's fine if that is your business model. But the business model here seems to be showing growth for the sake of wall street as opposed to growing the business in a meaningful manner.
Linkedin does serve a purpose it allows people to humble brag which is helpful even if they aren't looking for a job and don't need the connections because, say they own a business (and I don't mean a startup but it could be that as well). It's become an acceptable way to show where you went to school, what you have done in the past, and where you work or what you are the owner of. There really aren't that many other ways you can do that w/o appearing to be actually bragging and trying to impress someone (meaning it's not the same as having a personal website or even pointing people to a link "about me" page on your business website or a wikipedia page.
What's amazing is that they apparently don't want to filter the bogus requests as opposed to merely the requests that are from legitimate people (not bots) and simply trying to build what appears to be a network.
For this reason, I'm somewhat lenient in adding LinkedIn connections, as long as I at least have some idea who the people are. Unfortunately, many connection requests are from people I've never met before.
In gmail, everyone you've ever emailed is in automatically added your address book. LinkedIn provides an easy (maybe too easy) way to upload your address book to LinkedIn.