You will need to understand why that's completely wrong before any comprehension of the aerodynamics of turning is possible.
If I could put that slightly less confrontationally...
We will need to agree on the meaning of the words we use before we can possibly agree on the physics.
Wikipedia does a reasonable job of explaining the conventional meanings of the terms
roll, pitch and yaw but even there the word "vertical" in the definition of yaw is unhelpful. The key idea is that the axis and therefore the angle is defined with respect to the airframe ("vehicle") not to the earth, nor to the instantaneous direction of motion.
An aeroplane in a balanced level turn (angle of bank between 0 and 90 degrees exclusive) has an angular velocity about a vertical (earth-vertical) axis. That angular velocity can be resolved, just like any other vector, into a different coordinate system, the vehicle axes, resulting in component about the yaw axis and a component about the pitch axis. Thus it can be said to both yaw and pitch.
If you choose to make the word "yaw" synonymous with "sideslip angle" or "change in sideslip angle", you may be able to reconcile some of the statements on this thread with the real world. But please be aware that this use of the word is not the conventional definition in flight dynamics.