brent
Really only talking about Solus packages. Flatpaks are a bit different as they are essentially all installed by you and the required libs just come along, so there really is no need for separated as it is all installed due to user.
Whereas with Solus packages, there are packages that are installed by Solus, mostly the initial apps and core systems, etc. Then you have the packages you install. However there is a lot of crossover for the most part and you will see some listed in User Installed that you may not have directly installed. Looking back at Solus SC there was just Installed and not broken down between the 2. Same thing with Discover and most package managers. So not sure if there is a real need as it is redundant as the packages show in "All", "Installed", and "User Installed". Maybe adding an icon, like @Xoph mentioned would be a viable alternative to showing it was a package installed by the user.
Basically trying to clean everything up both on the front end and back end now that we have the core features. That makes it easy to maintain and add new features in the future.