Its all about having a stronger onpage optimization done than backlinks. So wont backlinking be part of 2018(relevant, niche ones') and also content marketing can be a big plus too. Content getting pocked up by high authority sites is a big Yes and needed as Google appreciates it. Nice details if someone is starting up with SEO in 2018 with new website, so its easy for them to do RIGHT from Day 1.
Additionally, there are many situations where PPC (a component of SEM) makes more sense than SEO. For example, if you are first launching a site and you want immediate visibility, it is a good idea to create a PPC campaign because it takes less time than SEO, but it would be unwise to strictly work with PPC and not even touch search engine optimization.