This is a source of great debate
The main reason (my understanding) is that although your axles are individual rated, GVWR is set by the manufacturer based on the entire "system" (in theory) - engine, transmission, suspension, brakes, frame/unibody construction, % safety margin applied, etc..
That being said, GAWR is arguably the most important factor (IMO) to ensuring you are not overloading axle, suspension and most importantly (arguably) your tires.
For example, I have a 2017 2500 GMC 3/4 ton class truck. I regularly operate above GVWR but still well within by axle ratings and CGVWR of TV+trailer. In my case GVWR is 10,000 with front axle GAWR @ 5200 and rear @ 6200 GAWR making for 11,400# total. I tow at 4600 front and about 5700 rear loaded / hitched which is 10,300#. I am still a healthy 500lb under my rear axle rating so I don't even sweat it. My tires are rating for > 7,000 lbs @80psi in the rear.
Literally the only difference between my truck and the 1 ton version (now that I have upgraded tires) is that the 1 ton has an additional helper leaf spring that adds 800lbs more WR to the rear axle, bringing it to 7,000# GAWR in the rear. Brakes, engine, transmission, differential, axle housing, etc are all the same otherwise.
So in my case the 1 ton simply squats a little bit less, maybe 1/2-1" @ 5700 lbs on the rear axle. I will probably add some air bags this winter to pull that black in a bit / provide for a little more suspension travel under heavy load (but have no plans to exceed my front or rear axle ratings).
When I towed with my infinity QX56 1/2 ton SUV, which had a 7500# GVWR, we regularly towed at 7750- 8000# on the TV loaded / hitched but with weight correctly distributed across the axles, so I was always under my axle weight ratings front and rear.
Everyone needs to make their own call on towing near, at or above GVWR.