Program names and "pollution"

Yes but at least it is obvious what package "createuser" belongs to in that case. If you don't add that directory to your path (which, unless you use postgres, you won't), you won't even see it. It won't break scripts, it won't clobber other binaries, the only issue is if there is another "createuser" in some other program's bin directory and for some reason you need to be able to run both -- but it's still better than putting both in /usr/bin.

Seriously, why not do this? Also, I guess newer systems like flatpak and snappy would basically be doing this.