Calculus teaches us the nature of optima. Sometimes they're at one extreme. Sometimes the sweet spot is somewhere in the middle.
This is one extreme. The sweet spot is in the middle, using tap/hold keys on a more conventional keyboard as supported by QMK firmware. It's brilliant to keep your fingers near home row. It's dogmatic to not have the other keys even be there, or to force yourself to use one hand if you have two.
A finger of one hand holds a key to select a mode, a finger on the other hand taps a key using that mode. This mode selection layout should be mirror images for the two hands. The Matias one-handed keyboard established beyond a doubt that our brains are wired to support this.
I use custom modes for punctuation, exotic "control-xylophone" editor commands, and controlling my computer. And yes, a cat walking across my keyboard will rearrange the orbits of the planets. However, the decades I spent thrashing would have been all worth it just to realize I shouldn't have to reach so far from home row for shift and modifier keys.