LinkedIn is not the network I spend the most time on but perhaps it should be. Facebook is where I connect with friends/colleagues on a personal level, Twitter is where I share news with a larger sphere, but LinkedIn, I'm finding, is actually where I learn things. That learning doesn't happen in the general stream which is mostly like the Facebook feed, 90% blather, most of it of little relevance or use to me, notifications of birthdays and job changes, or buzzword-filled articles reposted mostly as proof of life, it happens in the groups. The groups vary widely in quality but a few well-chosen groups can be truly beneficial to your professional life. People share real information and ask questions that truly matter. Interaction is mostly courteous and professional and often encouraging.
For example, this week, I learned about a change to the notary laws in California. I'm a licensed/bonded notary. I don't use my seal much at all but still the change is of interest to me. I wouldn't have known about it without an email notification from a notary group I'm a member of on Linked In.
There are of course also Facebook groups for businesses and I'm members of those as well but the tone is different. They quickly slip into insiderism and the tendency to form cliques seems much higher on that platform. The camaraderie, while enjoyable, erodes the usefulness. Also the LinkedIn groups are often served to me by email which is naturally the place I work out of most.
I belong to groups for luxury marketing, real estate, content marketing, journalism and more. Many I've joined and then abandoned, there are only a few I participate in with any regularity but I'm always changing my social consumption mix. LinkedIn groups are increasingly places where I find that the ratio of signal to noise (or information to nonsense) is more tolerable.