> On the other hand- crates.io + the toolchain make it way easier for fixes to propagate outward into the ecosystem, and then for new builds to be created with them (even for multiple platforms at once)

As a Rust fan who subscribes to the classical Linux distro model (and even exclusively gets his Rust crates from there), I disagree. What you suggest comes with a cost, namely having to accept software in constant flux. To me, that cost in unacceptably big.

I write a bit more about this gripe here: https://news.ycombinator.com/item?id=32925491