You don’t put roller bearings under a rack, silly
@geoffkait - Not always silly -- Grand Prix Audio Apex footers are roller bearings and they work perfectly under all my racks.
I also think you are incorrect in regard to speakers -- the whole point of the Townshend video and explanation is to discuss how small displacements front/back in the speaker can affect the sound, their spring based solutions have some lateral flex so can move in both vertical and horizontal planes