I guess it works as a very high level explanation. However, as a practical guide to designing an actual working airplane wing, it's probably too high level to be helpful. For instance, if Newton was a complete explanation, then a flat wing at a 45 degree angle should work well. A more complete explanation would also explain why airplane wings typically have the shape they do.
I don't know if 45° wings provide good lift or not, but what I know is that they would induce a lot of 'drag'.
And that the goal is to maximize lift while minimising drag..
So it isn't that complicated why the wings are the shape they are: if there is a 'gentle slope' the air will be redirected downwards without inducing too much drag.
A flat wing at 45 degrees produces massive turbulence above and behind the wing, which in turn greatly increases the drag-to-lift ratio compared to a standard airplane wing. Also I suspect that ailerons and other control surfaces become much less useful in turbulent flow.
