If these claims were true, we would have seen some examples by now. Instead, we get some tired invocations of "leftpad!" along with some more tired FUD. Who has been hacked because they used javascript instead of some other "more mature" language?
We've all lived with code that was 5+ years old, even if not all those years were ours. b^) Often that meant wrangling envars to point to the right ancient binaries, assuming we could somehow get those binaries installed. None of that is required with javascript. If a dependency is causing problems, just replace it with a different one. (npmjs.com has lots of packages!) Or, write something yourself. In five years you'll find enough spare time.
