These are the justifications of developers who are unfamiliar with the Intent system. Were I unaware of Intent, I would make the same design decisions.
Intents are the idea that your app doesn't directly request camera permission, for example, but instead asks the system to open a camera screen, and another app (or even your own app) can then respond to that.
This provides more choice, and reduces the amount of needed permissions.
Signal used to use the camera intent, it was changed to use direct capture so the camera opens faster and so captured photos aren't stored in the camera roll.
