I agree it's sometimes confusing as to why a particular app needs a specific set of permissions but I think it's down to the way the app is written for it to integrate with the phones settings.
Some of these apps need several permissions which makes me think again about accepting them.
One Play Store Notes App needed way more than I was comfortable with so looked around for another.
You might be able to contact the developer of the app to ask the specific question.
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.
