Throwing in my two cents:

I would imagine package managers are because of C and C++ not having package managers. I remember 20+ years ago before package managers were a thing, before the Debians, Ubuntus, and Arch (btw)s (before autoconf and configure), when we would download software and have to compile it ourselves, and the lack of reliable means of knowing what dependencies were needed to compile said software. Repeat this ad nauseam for each dependency that itself had dependencies.

It was Hell.

I for one am grateful for my dependency-resolving overlords. 🙇‍♂️

It's because it's the greatest thing since compilers. Having a clear "this is how packages interact" rules and "autodownload dependencies" solves a massive headache. C/C++ packages are basically the wild west.

As people grow up, they stop believing in magic

If you've ever tried using bazel, you might understand why writing a single package manager for multiple languages is a bad idea (at least, that's why I assume bazel is so god-awful)

Do any serious portable project with C and you'll see why. You'll either need to vendor in all the code you want to link against, or you'll constantly have compilation issues when the OS provided library differs (or doesn't exist at all) from the one you have on your dev box.

i dont understand why you are confused. are you suggesting they should be in the OS? so each library has to be managed at least 6 times and then the ides and language tools have to support all these different stores? i bet ci/cd would just be awesome

or are you suggesting that all language maintainers work together in harmony and support one another?

C and C++ dont have package managers because they are older than the concept.

I think that nix might be on the way to solving that problem. It does need a lot of work though.

lowers barriers to adoption of the language and its ecosystem

Because professionals have standards.

Because you don't want a single operating system manage the entirety of the Rust eco system. They need to be its own thing, so it can be used and managed by an individual team independent from any operating system.

In the case of Rust, it makes sense both as a UX win and a way to abstract certain requirements of the build system. Languages don't agree on how to do things like linking packages into a binary or versioning packages. If Rust left all of that unspecified, we'd probably have multiple competing package managers and ecosystems.

Reminder that TIOBE is ass and shouldn't be used for basically anything except for who to target advertising to.

The OS package manager is basically the C/C++ package manager. :P They all have OS level aspirations. Don't let them.

You want some way to define package versions in your repository, so that you can check out an earlier commit or a different branch and still have a working build. Because you do often need to adjust the code in your repo when dependencies get updated.

And going upwards from there, I think that languages are just a point where it's quite natural for this to be solved, since the language creators care to build up an ecosystem and it does help when you can make language-specific assumptions.

I do think, it's possible to create a package manager that spans across programming languages, like Nix is starting to be viable for.
But you need that to be ready when a new programming language is starting to take off. For all the languages you listed, that choice was made many years ago and you can't easily reverse it.

I agree that this doesn't seem necessary. Personally I think Nix would be a good candidate for dependency management that works consistently between languages. I think that may be partway set up for Haskell, and I've noticed that nixpkgs has a good collection of Python dependencies. But for most cases the Nix flow currently usually involves using the language's bespoke dependency manifest to generate a Nix expression that downloads dependencies from the language's bespoke package repo.

One advantage of Nix is that you don't need all packages in one repo. Nixpkgs is mostly geared for the NixOS Linux distro. Each language ecosystem could have its own repo if that makes the most sense, with Nix being the common connective language.

For the simple cases, a language package manager is easier to write and makes things easy. However, simple cases aren't at everything and for the more complex cases, such as what C and C++ is commonly used for, a language package manager is not complex enough to handle all the little weird special cases and so it would be a bad idea.

Those who use a language for something complex will not use the built-in package manager. Realistically though, very few people are writing complex software and so this objection, although real, is probably a pedantic thing that doesn't affect you.

What would be the alternative, exactly?

Well, as a user of DSL (G'MIC), I'm happy without packages.

It’s because every ecosystem wants its own GovOS.