Indeed, but from your own original comment - we have hindsight. So we can build an excellent std lib from the get go.
There are other bundles that are very popular for a reason. Conda. That's all you need to know. People want stability of dependencies, not wild wild west on pulling libs from random github repos.
IMO the bundling and curation is the least interesting part of Conda. What's really nice are the build infrastructure, quality checks and proper dependency bounds (looking at you, PyPI). Something like R's CRAN already has those without bundling.
And now we have Mamba, which is just like Conda. Except it has a better-documented (and more open) tooling ecosystem. And it lacks the debilitatingly slow/unreliable dependency resolution of Conda.
There are other bundles that are very popular for a reason. Conda. That's all you need to know. People want stability of dependencies, not wild wild west on pulling libs from random github repos.