There are user, upstream and distro configurations.
App xyz might require having a settings.conf that defines certain paths and enables/disables settings. A distro may wish to provide sane defaults and the user might want to make modifications to these settings. Historically these settings goto /etc/*
If all 3 use the same space this causes a 3 way merge conflict when upgrading a package. Something you still occasionally see on distros like Arch where it asks what you would like the package manager to do, i.e which settings.conf is authoritative. This requires users to decide something that might cause breakages or reset their changes.
Solus tries to use a stateless configuration. Our defaults are in /usr/share/defaults/* this is the systems space no user should edit files there. Ideally leaving /etc/ for user changes. A good example of this is samba we ship our sane defaults https://dev.getsol.us/source/samba/browse/master/files/smb.conf.solus users can override them in /etc/samba/smb.conf
This way user changes are respected, no end user interaction is required when updating and if a user makes changes that break something they can simply delete the file they added to restore the default configuration.
NOTE: Not all packages are stateless but it is the goal to make them so whenever possible.
