Good points, but I would suggest that just because the swamp-dwellers like it that way, does not mean it isn't a swamp.

I very much minimize my time there, because it is the spammiest, clingiest "social" network I've tried. I abandoned Facebook too, but there is at least marginal usefulness on LI, so I log in periodically.

I'd say that those who engage most are either directly recruiting or marketing, or self-annointed "thought leaders". At least the recruiters are unashamed in their role there. I cringe most at the thought leader types who apply the term to themselves. Like "hacker" or "guru", the term should usually be given by other people.