This definitely must just be a “what you’re used to” because I find using ctrl for a modifier to be far more “contorting” than moving my thumb a bit to the left or right of where it’s already naturally sitting for the space bar, and my thumb is a “stronger” finger than the pinky so it also just feels easier on the hand. So much so infact that I remapped the right hand command key to ctrl in emacs (with the usual capslock-> ctrl remapping for the left hand) just to make it more comfortable.
You're probably right!