But I think their tooling and policies have become outdated, which prevents faster progress.
I wish they would switch to some Nix-like alternative, which was discussed in their developer list long ago. The genius of Nix is that packages do not need to depend on the same dependencies. Hence, the whole package tree does not need to be kept in sync.
Another great advantage are declarative package specifications. I maintain several packages for NixOS, and a bot does auto-updates for me. I just check upstream hasn't introduced any malicious code.
Lastly, shipping many "distributions" becomes trivial with Nix. A distribution is just a package channel plus a declarative setup written in a small half-a-page expression. So you can easily create a minimal Debian, a Debian with a GNOME desktop, a Debian with a Xface desktop, a Debian with a KDE desktop, etc.