HN is so averse to anything related to marketing, conversion optimization, or anything else similar to such practices that a whole new title has emerged simply so no one has to grimace when saying they need to hire a "marketer".
Call a spade a spade: growth hacker == marketer. Yes, they use data to lead their decision making process and are more empirical than traditional mad men style marketers, but that by no means warrants a whole new job title.
Growth hackers are just good marketers using the data and tools available to them.