I disagree that "someone just has to build it." For example, when iOS shipped it did not have spell checking, word lookup, translation, password insertion, etc

I disagree that "someone just has to build it." For example, when iOS shipped it did not have spell checking, word lookup, translation, password insertion, etc built in as context menus on text. When those features were added by the OS, every app using the native widgets got those features for free with no work on their part. Apps that rolled their own though, had to re-release their app. If they don't have time or their app is abandoned then their users suffer. This is arguably one of the reasons flash was killed off. It was designed to render to a rectangle of pixels and it assumed a mouse and keyboard. Then smartphones appeared and no one was going to go back and fix millions of flash pages. Current apps doing their own thing will have the same problem with the next UI change (maybe vision Pro for example).