What I don't get about articles like this, is that the growth is just taken for granted as if it's easily replicated. It's all about hard-fought learnings about product/ops/GTM, and none of that is relevant if you don't come up with an initially compelling product. How can you nurture growth if there is no growth in the first place? Maybe I'm a dumbass who just doesn't "get it," but it seems to me like a premature victory lap to celebrate these learnings before proving that they are fundamental to repeatable success.
Of course, each social app goes through various inflection points and arguably celebrities is towards the peak end of it. Celebrities usually catch on once it's already going mainstream or has a mainstream appeal. For example, Twitter had already created strong base of engaged users before celebrities caught on.