My experience is that it helps with being able to look at screens, but not that it is better than not looking at screens while riding. I needed to occasionally leave the screen and close my eyes or look outside (depending position in the vehicle) for a bit to calm down. But otherwise I cannot look at screens on rides for more than a few minutes, so it is better in this sense.

So yeah, as somebody with (moderate) motion sickness, this advise resonates with me to some extent.

It's not for general motion sickness. Most people only experience motion sickness when they're moving but their eyes aren't seeing any movement, such as looking down at a something. That type can be prevented by simply putting down the phone/book/whathaveyou, and looking out the window. I said prevented, not cured, because once it sets in, no amount of looking out the window will cure it.