But if you look behind yourself your head is pointing away from the screen.

Not necessarily if you've got a curved ultra-wide display. Combine this with some rotation factor and you can look around while still looking at the screen.

Typically people don’t use 1:1 movement when using something like this. It’s a much higher ratio so you only have to slightly move your head to look around. It allows you to do it quicker but also avoids exactly what you’re describing.

It's not a 1:1 link with these, turning your head only slightly is enough to look behind in game.