There's no need to actually use all these complex tools if you don't want to. We wrote a pretty large (>20kloc) React application with a simple require.js based build flow using a Makefile that invokes a couple of tools for bundling the JS and generating assets like CSS. We used our own resource loader framework based on jquery (Redux didn't exist at the time) and a simple routing library (director.js). Still works like a charm!

In my opinion, the important thing in frontend development is to know which tools and libraries to adopt and which ones to ignore.

As a platform, I find JS+HTML5 really appealing and I'm happy that there are many ways to use and creatively remix these technologies, so I don't see the large churn in the ecosystem as a disadvantage but rather as proof that browser-based JS works very well as a platform to develop applications on.