Link building will always be essential. However, how you approach this today is quite different to how it was done 10 years ago. Today's biggest challenge for businesses is how to find customers and sell. Search engine optimization can help with this.
Nowadays, businesses need to use social media, and content marketing strategies are also very important. Google penalizes websites which have too many links to their sites. This is understandable since linking to too many other sites will likely mean that there isn't much original content on your site.
All of these factors make link building less valuable in ranking websites.