Think of a steady loop. Pitch is increasing as the nose comes up, but alpha is more or less constant. Pitch rate high and positive, alpha rate zero.
Stall warning and avoidance systems essentially interrogate alpha, for alpha defines the stall. However, if alpha is rising rapidly toward the stall value it would be prudent to start the warning or recovery before the whole thing overshoots and turns to worms. Therefore modern stall warners interrogate alpha rate as well as alpha.
Dick W