Meanwhile, cargo works flawlessly on every system I've tried (Linux, Mac and Windows). Sure, it only compiles Rust programs, but there's no way that I'd advocate moving those programs to a package manager with as little regard for such a large part of its potential userbase.
Or that they just don't have enough manpower to actually support all the platforms.
At a minimum, Linux should have a common packaging system; though there may never be agreement. It's hard to see macOS and windows endingnup with a common one.
But maybe we could do a third party option that is independent of each OS? Those rarely work out well though.
As an example, IBM just released yesterday a new mainframe model.
z/OS is a totally different animal compared with POSIX based OSes or Windows, starting by the file system, catalog based.
What is the alternative? Every major Linux distro has its own repository, as do all the BSDs. The picture on Windows and macOS is even more convoluted. Are developers in all these languages supposed to support the packaging of their software in half a dozen different repositories?
Maybe all programmers should get together and build "one repository to rule them all"? I have no idea how we herd that many cats!