This infographic by http://www.smeinsider.com/ highlights some numbers that show how attractive LinkedIn is and why it should be included in your marketing system.
You can begin conversations in groups, share content, write and share articles, have a detailed profile, etc. Your efforts can bring traffic to your digital properties, lead to conversations, create leads and so on. These connections aren't random, they are people who have likely seen your profile and read your contributions and have chosen to communicate with you. While the numbers may not be as high as other social platforms, the people on LinkedIn are much more focused and likely to be good leads.
Do you use LinkedIn? What works best for you?