The actual need for developers is usually much smaller, but they have to appear to be growing for investment and expectations. Same story for Snapchat and many other startups turned IPO. Usually a small team works their butt off to get it going and not many more are needed to maintain it and only a few more to add new features. That's why a lot of those jobs were basically to be on call (at work) to get certain projects done and meet together between eating meals, playing ping pong, napping, etc. So then you cut the fat to the tune of 80% and provide basically the same service once it's all set up and going. Maintenance different than innovation.