Oh, it makes perfect sense. This feature makes it possible to work on a project with only the component packages loaded that this project requires. That reduces the IDE memory print, especially if you have a lot of 3rd-party packages installed (these things tend to breed if you don't look 😉), of which the current project only uses a small subset. That was certainly more important in the early times of Delphi (D1, Win16!) but can still make a difference today.
You can drastically reduce the IDE start time, for example, by using a default package set that is the absolute minimum, basically only what is needed for every project you work on. Other packages are then only enabled for the project that needs them.