Whenever I go on linkedin, I'm spammed with an insane amount of articles about 'leadership' which are written in the worst kind of HR'ese by people that are blatantly trying to promote their brand. Facebook and Twitter are interesting because people share cool things which I like reading.
The kind of content that people create/share on linkedin makes me want to gouge my eyes out. Don't even get me started on 'influencers'. Ugh.
So - the problem with professional social media is that people sanitize everything so much that it's completely uninteresting to read. You could have a wonderful product, but it will be a beautiful shell filled with meaningless self promoting garbage.