Or to put it in other words: browser technology is asked to do so much that they had to go invent a new language to keep up. So that they could serve ads.
For us ordinary folks trying to write good applications that can be maintained by one person and scale reasonably well, there's justifiable reason to jump off this rollercoaster and work in a more humble environment with modest perf/safety tradeoffs and native code executables(e.g. Go, Basic, Pascal).