IMO it shouldn't contain that feature. There are high quality apps for locking access to apps with loads of functionality and customization this developer simply won't be able to match, because it deserves a whole app on its own. Why not use these?
iOS perspective: Because apps can‘t have this far-reaching permissions on other apps (and, adding my 2 cent, that‘s one of the reasons I still stick with Apple, even though their hardware and software quality is steadily declining).
