In SEO, The purpose of SMO is to use social media to increase traffic to a website. It is important to generate viral publicity. For getting the complete information about the what are the importance of social media, Visit this site : https://www.screamingfrog.co.uk/social-media-and-seo/
Social media really plays an important role in SEO because:
social media helps in increase the brand awareness on various social media platforms and search engines.
it drives high quality traffic to your website
it increase the visibility on search engines etc.