LinkedIn works via active participation.  However, as a job/employment site it has the potential to be harmful to majority of its users should many subjects or even the quality of articles covered were to be given candid, honest responses. 

One concern often discussed in Networking groups is the harvesting of job seekers resumes by unrepeatable recruiters.  A second though unintended consequence is the opportunity for hiring managers or generalist to preemptively filter out qualified minority job candidates.  This mitigates the old "shameful" practice of discovering the race of a candidate at the interview and having to dismiss their candidacy under the guise of... you name the mired of old excuses...

Brush up on your LinkedIn know-how with these tips on how to navitgate LinkedIn groups. You may get invited sometime soon.