It's a feature, not a product, doesn't do everything that Keychain Access does in macOS, and doesn't need (or deserve) to be in your face all the time.
Do keyboards/wallpaper/voip apps/whatever really need to have their own app icon on your homescreen? Probably not, but Apple's conditioned us over the course of 15 years that all apps have icons you can see - a view at odds with things like Fantastical and SwitchGlass, which are really "apps that run in your menubar" and can be used without a Dock icon at all.
iOS doesn't have the concept of "Utilities" within "/Applications" like macOS does, but maybe it needs to in order to address this class of app which has such a specific focus.
After 15 years, are we at a point where some of the early affordances aren't neccessary anymore?