> package management belongs to the os

Os package managers do a fundamentally different task than dependency management tools used in development.

They ship a bunch of applications and the libraries you need to run the applications.

If you need different version of libfoo than e.g. Firefox does, you're out of luck.

Need to support a customer with an older release which needs a different version of libfoo? Not gonna happen.

Unless you're talking about Nix or Guix, your OS package manager is not a substitute for a dependency management tools.

Fair enough. The world needs a package manager that is language agnostics and provides input to OS package managers as well as build tools (which should also be language agnostic).