Why is the 'standard chord' for Dorian b9 a sus chord? More specifically, a sus4. Instead of stacking triads, i often see people (most notably Rick Beato on youtube) use a sus chord on the first step of this mode. No real explanation is given anywhere apart from' this is the sound of the mode'.
Does anyone have an explanation of why we use a sus4(maybe add a b2) as the base-chord of dorianb2? And why do we not translate this further trhough the scale when we keep stacking chord tones? E.g. in Adorianb2: First chord is A, D, E; second chord is Bb, D, F#. Why not Bb, E, F#?