I feel like Apples M.O. on software is to build the lowest passable set of features in their apps, never enhance them, allow third parties to delve into the high functionality/spec software. Mail is horrible, Camera good enough for most people, for me personally even Safari is in this camp; I’d swap any of those for a third party solution without much thought. Phone app becomes a bit to much of a security risk to use a third party, such that I’d never even consider leaving the default Phone app.