I'd actually say that its less about instability and more about rapid experimentation. There's two main catalysts - the youth of single page web apps and the o

I'd actually say that its less about instability and more about rapid experimentation. There's two main catalysts - the youth of single page web apps and the openness of the modern web. The complexity of your everyday website is increasing as they move from static sites to web apps. The pressure to be as responsive and fluid as a mobile app is high, and that requires solutions for data management and synchronicity. There is no standardized way to solve these yet. When you tie this increasing complexity with the free-form structure of the web (there is no recommended way to build a web app unlike mobile apps or to a lesser extent desktop apps), and then add the growth of JavaScript from a toy language to a full-blown complex ecosystem, you get even fewer established practices. This is not to say that there will never be best practices but rather that what you're seeing is a language scaling with its needs without having a central dictatorial entity at its helm. You're seeing unprecedented growth and that can easily be confused with chaos and instability.