Isn't this due to inherent limitations of native binaries? Java has very few native dependencies, so its trivial to do binary dependencies. Besides, most packages in maven central have their sources in there as well. You can easily download the source package and let the debugger use that.
No, had nothing to do with native dependencies, they are even more rare in Elixir than Java. It’s simply a different choice in the design.
I know that I can step into a source package with the debugger, but editing that source and rebuilding doesn’t compile the change into my build does it? The last step of debugging is fixing the code, its much more convenient to first try this in the same project where you encountered it.