That is correct. If however your clutch pedal resides on it's own independent pedal box and you don't touch the brake pedal box, you are fine. So long as the clutch pedal doesn't hit the wider auto brake pedal.
The issue is, people in the past have modified their factory brake pedals to fit around their newly installed clutch pedal, they did a shit job, their brake pedal broke and they no longer got stoppers. Hence blanket rule to make sure muppets haven't stuffed anything up. All it takes is one mounting point to be in a different location and someone going "meh, doesn't need it" and then eventually the frame fatigues and things go wrong.