Even with the rising of social media, there's a usefulness to back linking... specially when it is done the appropiate way. If it is honest, real back linking, that's a good indication of your popularity as people will linking to that website for the content itself.
Of course, the amount of backlinks may help your ranking (that is, if the webmaster that's linking to you allows that. The link may be no follow). But the real importance come from the fact the name of your site is being seen by a larger number of people and, again, if done the right way, it will give you a good reputation and trust is everything in business. It means traffic and, in the long term, profit.