I personally rather dislike most Social Media, but it has proven invaluable for helping clients and my own websites build an audience, or sell product. Twitter can be especially useful for customer service and announcements, and YouTube probably provides the most valuable SEO boost when used well. If your target audience hangs on FB or Pinterest or IG, FB groups, Pinterest Boards and IG stories not only help rankings but really help develop a relationship with the people who hang there because it's so easy to target a specific demographic.

Lately I've noticed Twitch has been giving a boost to rankings as well, especially in regularly scheduled streams in finance, news, interviews, and the cryptosphere (and of course the gaming world). I'm hopeful that DLive and DTube will also send a strong signal as well.