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1) If it helps to get more links, the links are “nofollow”. However, I read somewhere that " Pinterest stopped passing link authority through its links to external sites"
2) Useful for Social signals and fresh content. Although that might not be helpful for google but Bing is already using social signals in their rankings
3) In many ways, social networks like Pinterest function as secondary search engines
4) Driving traffic to your site
From a personal experience, I did not get much traffic from Pinterest .. However, Pinterest links can be seen when checking the Google console "links to your site" .. Whether it is worth the effort or not .. I'm still not able to answer this question!