"Give app X direct access to the camera, microphone, and all my photos literally any time it pleases" and "use this camera app I trust instead" are very, very different desires.
Usually I hate the in-app cameras, because they're not optimized for my device. They're usually slower, have no flash control, no zoom, no manual exposure options, etc. I'd almost always prefer to use a dedicated camera app instead.
Because of this permissions decision, if an app wants to bake in a camera thing (nearly every app that might ever touch the camera does, even if e.g. only for a QR code reader or something), I can no longer choose. The app can't open my camera app when it makes sense.
