It appears to me like the linked explanation is also subtly wrong, in a different way:
“This is why a flat surface like a sail is able to cause lift – here the distance on each side is the same but it is slightly curved when it is rigged and so it acts as an aerofoil. In other words, it’s the curvature that creates lift, not the distance.”
But like you say flat plates can generate lift at positive AoA, no curvature (camber) required. Can you confirm this is correct? Kinda going crazy because I'd very much expect a Cambridge aerodynamicist to get this 100% right.
Yes, it is wrong. The curvature of the sail lowers the leading angle of attack which promotes attachment, i.e. reduces the risk of stalling at high angles of attack, but it is not responsible for lift in the sense you mean.
It could be argued that preventing a stall makes it responsible for lift in an AoA regime where the wing would otherwise be stalled -- hence "responsible for lift" -- but that would be far fetched.
More likely the author wanted to give an intuition for the cuvature of the airflow. This is produced not by the shape of the airfoil but the induced circulation around the airfoil, which makes air travel faster on the side of the far surface of an airfoil, creating the pressure differential.
“This is why a flat surface like a sail is able to cause lift – here the distance on each side is the same but it is slightly curved when it is rigged and so it acts as an aerofoil. In other words, it’s the curvature that creates lift, not the distance.”
But like you say flat plates can generate lift at positive AoA, no curvature (camber) required. Can you confirm this is correct? Kinda going crazy because I'd very much expect a Cambridge aerodynamicist to get this 100% right.