These discussions always kind of irritate me. They have ever since I started in the industry in 2007. I came from a physics background, so I've never had any formal business education. Why do they irritate me? Because in the face of business uncertainty, people have tried to break it down, make it scientific. You get all these buzz words like "growth hacker" and "viral", "social proof", "social lift", "Landing Page", "hypergrowth", "net promoter score" etc. And then people start asking these questions like "how much [buzz word #1] do I need to increase my [buzzword #2]". People like to pretend that these buzzwords are real things, independent from the reality of your product and the people who consume it. Maybe I'm naive, but for what I've seen so far, there are only 2 factors that drive 90%+ of any tech business.
1. Market demand.
This is the whale. Probably accounts for 60% of that 90% or more. Most companies don't sufficiently test it before throwing money at product development. Straight up, if you are serving a hungry market, they will shower you with money even if your product is mediocre.
2. Product Execution
This is, of course, measured absolutely and relative to competition. If you're early to market, you can reduce the competition factor and win even with a mediocre product.
If these two things are in place, the marketing factor doesn't take a lot of creativity, just activity. Certainly, you have to do some marketing - get your product boosted via influencers/bloggers, put a share button on things, form a mailing list, FB Page, etc. Certainly, there are certain types of products that will spread faster than others (i.e. communication products that require both people to be signed up). But you don't need to be a pioneer with some new gorilla marketing bullshit.
Without demand and execution, you're not going to succeed in the long run no matter how good your marketing is. So I look at a company like Ello or Secret, and I think their fast early growth reflects a perceived demand in the market place.
In other words, a lot of people have a problem they want solved -- dependence on Facebook or a sounding board for their dirty personal crap. But their overall success depends also on executing against that need. I glanced at Ello and could tell it didn't offer me enough. Secret was interesting for a while, but then it seems Quora is maybe a better platform for getting sincere feedback anonymously, and I started seeing the same types of problems over and over without any creative way to resolve. If you grow really fast, it can be difficult to execute fast enough to keep up with that... but it can also be difficult politically within a company to make the dramatic changes necessary to keep your product execution up to snuff. There will be people telling you to keep doing the same thing because it's been working so far. It takes power and courage to change, and frankly most people, even entrepreneurs in Si Valley, don't have enough.
I think part of the problem is such a high dependence on VC funding. Entrepreneurs don't feel like they can pivot after they've talked up a certain strategy to investors so far. They don't have full independence. I think this could be improved if startups moved elsewhere, needed less funding, and bootstrapped more often. We'd see better products. We'd see more courageous products.
You could also look at a business like Dave Ramsey's Lampo Group. It grew over a long period of time, and it didnt' grow at the same rate as Secret or Ello. But his instructional materials end up being effective at solving a big problem (personal finance), so people use them and recommend them. And now the guy is worth $50M+, and consumer debt is as high as it's ever been, so I don't see his customer base slowing down any time soon... so no wonder he has 400 employees and growing.
My point is that separating out "growth" as its own thing - having a theory that says "fast viral early growth will cause a burnout" is really not all that useful and probably missing the point. Bottom line for each of these businesses: How much market demand backed by $$$ existed for the problems they claim to solve? Did these products actually solve those problems?