[Manal]

I think that social media links are quite unrelated to SEO in concept and not going to increase your pagerank because these links are nofollow, but the traffics themselves can still be useful.

So if the social media accounts are powerful enough and have good number of followers, one might still get benefits from web traffics via these accounts.

That's incorrect. On Facebook, except page's website link, all posts link and other things have no "no follow" tag. The reason why search engines do not prioritize the link posted on social media despite those sites having 100 domain ranking, is because everyone can get a link there. If everyone can do that, anyone with low quality and another irrelevant targeting can get on the first number. So the website where getting links are hard and rare are prioritized the most because they bring you authentic and are not crowded. (This is based on my personal experience and is not verified).