I only know Node and Python well enough. I find with NPM that dependencies are indeed hell because anything goes. With Python it's slightly less bad because packages have a fixed tree of versions (although I don't know what's up with Conda or others yet), not to mention the more extensive standard lib. I suppose if there are real conflict workarounds required you could always use virtual environments all the way down, but I have generally just done whatever upgrading is required to resolve incompatibilities (which can sometimes preclude using third-party deps or require forking and upgrading their own deps).

I also remember from years ago that Bundler in Ruby allowed version mismatches to coexist and would install both deps in the same tree, punting any runtime issues (same as NPM).

Any Gentoo or NIX users might have something to add here, as I can remember being regaled at conferences by them about this topic.

All that said, it would seem that Rust could have some kind of super-intelligence about dependencies due to all the static goodness. So my questions are:

a) who cares how much is userland and how much is std lib if everything is equally safe and documentable?

b) if "too much" becomes std lib, could any feelings of overwhelmingness not be mitigated with more namespacing?