Tool for keeping track of packages of interest
The set of packages a user might be interested in are not identical to the set of packages they have access to, even within a distribution's main repository:
Once multiple repositories are involved, the situation gets even more complex:
Sysadmins and power users might also be interested in the same set of packages across different distributions, likewise with upstream software developers who are interested in tracking their software (and dependents and dependencies) as packaged in these distributions