I use it for looking in the camera. If I don't have the zoom window on my teleprompter, I find myself looking at the zoom window. Probably not a huge deal for folks using just laptops and occasional zoom.

I find it even more useful when recording courses. I use OBS to overlay my face when talking about code. I immediately notice when folks try to do this without a teleprompter. They keep gazing off to the side.

There are yt tutorials about making cheap teleprompters. You could try it out and see if you care for it. I made two, however the value in a real teleprompter is the sturdiness and the mount. It was easier for me to buy one than hack one up that I would be using everyday.