Because having the smaller profile in your pocket, but being able to fold out to watch content on a higher screen is completely different than zooming….

Sure you can zoom in on a YouTube video, but why? You’re just getting a nose or something instead of the video.

The fold is for when you do most of your stuff on the small screen, but want the big screen for certain things and don’t want two devices to do it. Which is the perfectly valid use case.

Taking a modern large screen phone on a run can be a pain in the ass. Why get a small phone and a small tablet when you can have a small phone that unfolds into a small tablet when you want it to?

It's not using it for directions, it is tucking it away in small pockets. I have a cycle computer while cycling, so putting my phone neatly and securely in a zipped pocket would be nice. But can't do that currently as the phone is too tall (pockets too small?)

Similar with running, doesn't fit is a zipped pocket all that well cause too tall, so have to throw it in a "food" pocket instead.