This is slightly misleading advice. The ideal place for the display has the top of the display at roughly eye level, or for a very large display maybe slightly above, which puts most of the display below eye level. Humans actually have great ability to look slightly downward for long periods of time while doing stuff with their hands, even while keeping their head held up straight, and indeed our eyes can more comfortably focus on close objects in the lower part of our field of view than straight ahead. What you don't want to do is slouch or bend your neck too much.
A laptop display attached to the keyboard usually isn't an ideal placement, but it's generally not too bad.
Welcome to "tech neck" - upper crossed syndrome, from looking slightly down.
You're inviting some surprising symptoms, not just neck and back pain, but things like numbness, tingling, or pain shooting down your arms. Really not fun.
Key posture correction seems to be pulling head back. Some physical therapy exercises can help as well.
https://deukspine.com/blog/tech-neck-forward-head-posture-tr...
In trying to picture this, I suppose there are certainly some stock photo models who'd feel the sharp edges:
google.com/images?q=person+using+laptop
I totally know what you mean about shifting positions. All the positions I've been in where I've felt the edges have been quite unergonomic, but perhaps not for everyone.