Earlier quoted context omitted.
If you strech out your fingers from your angled wrist they will follow the angle because the joints in our fingers have only a single degree of freedom. Do you reach for the key vertically above and below or do you angle your wrist 45° and reach for the diagonals? With a staggered layout the angle is somewhere between and similar to what most people angle their split halves.
With a staggered layout the right hand digits align with the columns and the left hand does the opposite; it's at nearly a 90 degree angle! So if you believe wrist angle follows the keys then staggered would be far worse. I don't think wrist angle follows the keys. You simply move your hands and fingers to hit the proper key regardless of wrist angle. No alignment necessary. So then the benefit of ortho becomes the a…
For these staggering was a necessity to prevent the typebars from clashing. The keys had a long travel and had to be hit with a lot of force from above like a diving eagle. Resting the palm was impossible and for a floating hand a short travel from key to key was more important than the angle.
A 2016 study[1] showed that consistency (always same finger for the same key) is a better predictor for typing performance than using a traditional 10-finger system or even ten fingers at all. Also the finger placement taught varies from where it is taught.
My point is that staggering doesn't make sense for a split keyboard and that most people unconsciously use the staggering of their regular keyboard as a poor replacement for a true split.
[1] https://dl.acm.org/doi/10.1145/2858036.2858233
EDIT:
"I don't think wrist angle follows the keys. You simply move your hands"
"minimal global hand motion" was the third best predictor for typing performance in the paper mentioned above. Unless you are typing on a Remington, anchor your palms and only move your fingers. Good for performance and good for your health.