What is the purpose of this library? It looks like it is ancient, not maintained, and replaced by librsvg.

It's a dependency for other things (libcutter) and it appears in Arch's AUR. It is indeed very old.

I'm super new to Nix so if in your estimation this doesn't belong in nixpkgs I'm happy to close.

We do not have any formal policy against adding old software but since this has been abandoned so long ago, it is quite probable there are many security issues not fixed.

Parity with AUR is not really our goal but if you find any of the packages depending on libsvg useful and want to use Nixpkgs to install it, that should be sufficient reason to include it into the package set.

More in-depth analysis would also weigh the expected future maintenance costs (more removed functions needing patching) and clutter against the usefulness of the package to other users and other subjective factors. NUR or personal overlays might be a good alternative to main nixpkgs repository in some cases.

I'll close. I wasn't familiar with NUR, but that certainly seems more appropriate.

Really loving NixOS! Thanks!