To Succeed, Growth Hacking Has To Focus More On Product Than Marketing

I think the author is missing the point. Even the best products can falter if the company doesn't know how to get distribution. Unless you're an extreme outlier, you'll need both great product and great marketing. And that's really hard to get in one person.

Relentless focus on building the thing the customer wanted vs focus on viral marketing strategies. That said, they had an inherent viral growth strategy by targeting their initial user base to a very sociable/vocal college crowd. That wasn't a growth hack, it was merely solving a problem that most college kids had.