Link building will always be necessary, but how you approach it now is different from how people did it 10 years ago. Finding customers and making sales is today's greatest challenge for any company. That's where search engine optimization comes into play.
Today, social media is essential for businesses. However, content marketing strategies and other tools are equally important. Google penalizes websites with too much backlinks, so link building seems less effective. This is understandable since linking to too many other sites will likely mean that there isn't much original content on your site.
All these factors mean that link building isn't nearly as valuable for ranking your website as it once was.