I've heard of people who make a living off of it and/or get their start (in music or art) on social media platforms. It's really good for helping a person break i to a career.

It's also good for connecting with old friends and for people like me I enjoy talking to new people. I've had a lot of support in rough times from people on this site and others. And typing fanfics and posting them on social media has helped me improve my writing as well as keeps me motivated to do it.
Same with art; people have been very helpful with me getting started on drawing.

social media creates communities, generates job opportunities, connects people, educates the masses, etc.
I feel it's important in this day and age