The problem with that is that no Linux distro maintainer will ever put effort into maintaining every version of every library and compiler perpetually for a specific, seemingly random, programming language (or at least, reasonably, within few major versions including all minor releases in between), but with a tool that versions dependencies and allows for, say, git-based upstream with tag-versioned releases, you can expect to pick any specific version and for things to just work; managing library code for a specific programming language, be it any language, does not seem like the responsibility of an operating system, if anything, the package manager from your OS should be able to just supply the tool to manage the said language (like you currently can with npm, cargo or go); that also does not touch the topic of making things work across different platforms, sure, you maybe found a way to solve this issue in your imaginary Linux distro, how do you solve the problem for a co-developer that uses Windows, or macOS?

Additionally, you do not have to necessarily enforce these things on the language level, the standard and the tooling could live as two independent projects coming from the same entity. You could still use the compiler and the libraries from your OS, and build the code like that, or you could just reach out to an optional standardized tool that serves as a glue for all the external tools in a standardized way.

Yes, there are a lot of valid concerns with this approach as well, but personally for me, as a frustrated C++ developer, who is most likely going to still use the language for a decade to come, I feel like all the other languages I had mentioned in my previous post had addressed what is my biggest point of frustration with C++, so it's definitely an issue that could be solved. Many tried to do it independently, but due to personal differences, no funding, and different ideas of what should be the scope of such tooling, we ended up with a very fragmented ecosystem of tools, none of which have yet to date been able to fully address an issue that other languages solved.