I think what the parent comment was saying is that when being held in a normal manner, the phone is facing about 45 degrees below the horizon, so it can't see much except people's legs. To film people's faces and such, you'd have to tilt the phone up much higher than you would if you were just writing a text message / email or browsing the web. If you try writing a text on a phone that's angled up to the horizon like that, it's harder to type and harder to read the screen.
True. I suppose the social conventions around overt vs covert use of smartphone cameras evolved before wide-angle cameras on phones became common, since wide-angle cameras on phones are a pretty new thing.
