Social media is usually used for referral traffic.
Having said that, your avatar links are usually dofollow ones, which transforms them into backlinks.
The better the content you share on social media, the more likely these posts are crawled and considered as good backlinks to your website.
There are naturally other attributes for social media, such as reputation management that shouldn't be taken lightly.
Yes, refferal traffic isn't enough to jack up overall traffic, but if it decreases the bounce and exit rate and perhaps even converts into paying clients or acquired clients that have travelled to other parts of your website - why not use it?