Yeah it pisses me off when i see it too, especially when it's some retard keyboard turner who is playing in some stupid burst team, they think they're so awesome by spamming APM like that - It's usually DKs/rets >.< Guess it's easy to strafe left and right while rolling ur dick across the keyboard.
EDIT - I mean players that literally strafe left and right while ur in a stun lock, there is literally no point for it.