https://www.youtube.com/watch?v=7zfir0Ide0A
Same conclusion that everyone has reached over the past four decades, at least. It even got a nickname.
https://en.wikipedia.org/wiki/Touchscreen#%22Gorilla_arm%22
Current Apple should show their new tests that demostrate the opposite.
(Edit) The full transcription of the video, faster than watching:
"You know, the first thing you think about is this, right? We thought about this years ago. We've done tons of user testing on this and it turns out it doesn't work. Touch surfaces don't want to be vertical. It gives great demo. But after a short period of time, you start to fatigue and after an extended period of time, your arm wants to fall off. It doesn't work. It's ergonomically terrible. Touch surfaces want to be horizontal. Hence, pads. For a notebook, that's why we've perfected our multi-touch trackpads over the years." -- Steve Jobs, 2010