Once you have created website submitting to webmaster tools or search console is very important. Even though it is not mandatory to submitting your website to Google. because with the help of links Google Crawler will find your website and crawl, but we dont know how much time it will take to reach your website.
Assume that you wrote one trending blog today and waiting the cralwer to visit your website. But crawler have visited your website after a week. At that time this trending news might be an old new. In order to get immediate results and attract huge traffic you have to crawl your website and you have to call Crawler with the help of webmaster tools or search console