> Debian could package every version variant ... Or, they could maintain immutability ... by having Debian Rust source packages contain their fully vendored dependency set. The former would be a lot of work, especially given how manual the distribution packaging process is today.
That would work for distributions that provide just distributions / builds. But one major advantage of Debian is that it is committed to provide security fixes regardless of upstream availability. So they essentially stand in for maintainers. And to maintain many different versions instead of just latest one is plenty of redundant work that nobody would want to do.
>... Or, they could maintain immutability ... by having Debian Rust source packages contain their fully vendored dependency set. The former would be a lot of work, especially given how manual the distribution packaging process is today.
That's not reasonable for library packages, because they may have to interact with each other. You're also proposing a scheme that would cause an explosion in resource usage when it comes to compilation and distribution of packages. Packages should be granular unless you are packaging something that is just too difficult to handle at a granular level, and you just want to get it over with. I don't even know if Debian accepts monolithic packages cobbled together that way. I suspect they do, but it certainly isn't ideal.
>And to maintain many different versions instead of just latest one is plenty of redundant work that nobody would want to do.
When this is done, it is likely because updating is riskier and more work than maintaining a few old versions. Library authors that constantly break stuff for no good reason make this work much harder. Some of them only want to use bleeding edge features and have zero interest in supporting any stable version of anything. Package systems that let anyone publish easily lead to a proliferation of unstable dependencies like that. App authors don't necessarily know what trouble they're buying into with any given dependency choice.
That would work for distributions that provide just distributions / builds. But one major advantage of Debian is that it is committed to provide security fixes regardless of upstream availability. So they essentially stand in for maintainers. And to maintain many different versions instead of just latest one is plenty of redundant work that nobody would want to do.