I am left handed and it never occurred to me that the dominant hand should brake the front wheel.
The left shifter handles the front of the bike and the right shifter handles the back of the bike.That’s how it was on downtube, barend, and stem shifting due to cable guide routing.So it only makes sense to apply the same thing to brakes.The left side of the bike therefore controls what happens at the rear and the right side controls what happens at the front.
With that said, I typically use both brakes when riding.Just makes sense to me- I have 2 levers, so use them.I may use just 1 to slow while in motion, but if I am coming to a stop either fast or slow, I will use both brakes typically.So it wouldn’t really matter which is set up for the front or rear caliper.
If you are setting up a bike for someone with difficulty squeezing a brake lever with 1 of their hands, it makes sense for the strong hand to use the strongest brake caliper.