I think mostly because of two things:

1) Imho an overly complex ecosystem (with thousands of dependencies via npm or such)

2) The "oh my god, that is 5 weeks old, there is something new, better..." mindset for JS-projects.

For long-term software slow velocity is a feature that has to be balanced carefully against stagnation... and not the "reckless" advancement that JS (and kubernetes for that matter) enjoys...

Most C-compiler-suites and most SQL-database move slowly, but move...