In practice, there is usually only a single dominant technology at a time even in the JavaScript ecosystem. See this recent survey: https://news.ycombinator.com/item?id=12627693

Right now it seems very clear that React, Redux, and Webpack are winners.

The difference, I think, is that many of these tools are simple enough that if you have a new idea you will simply write a replacement instead of trying to work with the maintainers to push out a dramatically different new release.