Key travel isn't the single cause for RSI. I don't have RSI pain with a mechanical keyboard with huge key travel for an example.
For me, key travel isn't the issue, it's the bottoming out impact. A lot of people are hitting the bottom really hard, which actually increase the chances of RSI.
My mechanical keyboard also has a soft bottom out so that I don't actually have to hit anything, just gentle tap and it's all good. I can't actually learn to tap gentle with low key travel like Apple's keyboards. Strangely, I don't seem to have the same issue on the iPad's smart keyboard.
Apple keyboards are the worst for me with RSI, it hits bottom hard and it's too thin.