You are thinking of OS or bundled "system" apps, aren't you? An independent app would invent an independent way of managing features.
And even though those devices might have a standard GUI for finding and editing them, each vendor either has a different way of importing/exporting them, or provide no easy way, period.
Plus, if they were standardized in an open way, you could install a different "settings browser" with fancier search, find, compare, query, report, alarm, etc. features.