Being to aggressive in breaking stuff gets you a shitshow like Node.js or Ruby. Long-term source code compatibility is a very useful feature for open source and a sign of a mature eco system. Feel free to add stuff, but once it's part of a stable release it has to be maintained long after a "better" way to do it comes along.
Javascript would heavily benefit from breaking changes. The reason why it still sucks ass to use today is because this won't ever happen.
I can't speak for node.js specifically but who gives a shit
> Long-term source code compatibility is a very useful feature for open source
Sure, until you need affordable maintainers. Maintainability must be balanced with patience for bad software. Cf the insane maintenance cost of perl scripts
nodejs itself doesn't have very many breakages; i have plenty of code that is unchanged from 0.12 to 24. npm is a whole other kettle of fish but I don't think you can blame the core project for the sins of everyone that publishes to the package manager. Python2 -> Python3 on the other hand had a lot of breakage in "standard" code.