My interpretation would be something like: the abandonment of software that is so poorly designed that it is difficult to package and/or run under Nix.
This commit message (from one of my commits) details some of the struggles supporting Ruby under Nix:
https://github.com/NixOS/nixpkgs/commit/b6c06e216bb3bface40e...
Each of those problems is due to either:
1. Some unmotivated contrivance in Bundler, where the maintainers refused to make their stuff less needlessly broken, or
2. Ruby programmers in general not programming with packaging in mind (haven't touched Ruby/Rails professionally in a while, but when I did, it was par for the course to rsync/capistrano files around -- no one saw the utility of any sort of packaging)
And the two really reinforce each other. Bundler is the de facto way to declare and pin dependencies at the app level, but then Bundler makes it nearly impossible (see the commit message for details) to package software using Bundler, which reinforces the "fuck it, we'll just rsync files around over SSH", which means no one pressures Bundler to Do The Right Thing.
It's the same thing everywhere else. There are complaints elsewhere in this comment section about the nodejs/npm experience on Nix: same underlying problem. The design behind npm is so unnecessarily shit-tacular that it kinda sorta just barely works on its tier 1 platforms. I don't envy the brave souls that have worked on supporting npm packages on Nix.