An IBM keyboard is not meant for a typist that keeps their palms resting on desk while slumping in their chair. It’s meant for you to sit up straight and hover your palms over the keyboard.
If you type like that then it seems effortless and the keys feel light and you’ll never have any wrist issues. Reaching the numpad area is also easy because your hand is already in the air. A proper typing technique is like jiu jitsu—it leverages the weight of your entire hand and arm to assist with the key presses. Your hand is loose and mobile, so nerve compression is less likely. On a chicklet keyboard your fingers are mobile but the palms are “glued” in place. This encourages lots of “flexing” the fingers to reach farther placed keys, instead of just moving your entire hand in the “hover” typist approach. My guess is this creates ideal conditions for nerve compression.
The pain is good thing because it lets you know you’re doing something wrong. Using keyboard with low actuation force is just masking the problem. If you do something wrong with less force you will not feel any pain immediately. Same thing as people using shitload of fluffy pillows instead of fixing their sleeping posture. If you sleep on floor it might be uncomfortable at first but it also forces you into better posture, instead of making it bearable to hold a wrong one.