Other package management systems do one or two of the following things, but I haven't found any that can do all three at once, other than pkgsrc:
1) have good availability of pre-built binary packages for most platforms
2) facilitate building of packages directly from source, whether on non-mainstream platforms / architectures, and / or with or for the purpose of non-default package options
Having to use more than one package management system because one or the other doesn't do one of these things can be a real pain, and can make maintenance rather difficult.
1) have good availability of pre-built binary packages for most platforms
2) facilitate building of packages directly from source, whether on non-mainstream platforms / architectures, and / or with or for the purpose of non-default package options
3) unprivileged builds / installations, packages rooted anywhere in filesystem, completely self-contained dependencies
Having to use more than one package management system because one or the other doesn't do one of these things can be a real pain, and can make maintenance rather difficult.