I think any NixOS maintainer would agree that the average quality of a package in NixOS is not as high as something like an official Arch or Debian package
Package maintainer here. Not sure what you mean by quality; as that term is very ambiguous. Shit works and configuration is often a breeze by comparison to other distros.
I would never go back to a legacy distro. Who wants to do that shit all by hand?
We can agree on this. There is work to do.
I run unstable, and I have had this happen twice. Both times with Tmux (which is weird); but it was upstream issues. But fair enough. Maybe my systems aren’t exotic enough to experience the uncommon breakages.
Could nixpkgs do better? Yes. I mean, look at the backlog. You have to be active in the community to get your work merged in any decent timeframe. I think this is the most annoying part about the Nix ecosystem.