My experience with LinkedIn @crypto.piotr is years old. Long before the Steem blockchain was conceived. My wife is on Facebook. I am not, nor will I likely ever be. From what she shares with me from Facebook, I view LinkedIn as Facebook for professionals. It connects business associates from all over the world.
Once connected, you can then share professional content that you deem may be of interest to your peers. It also allows you to maintain personal contact, if desired, with those whom you may have worked with many years ago (as in my case) and it is nice to see how they are doing.
As far as any downside, I was not too happy when it was sold to Microsoft. As you may know, Microsoft has historically bought up many, many firms to establish itself in new market areas, rather than build their own presence from scratch. At the time of their purchase of LinkedIn, it was the single largest purchase they had ever made - $26.2 billion USD ...