Not argumentative at all. There's a fine line between positive and negative, and fan count is only a partial player. It's mostly derived from the amount of pull the rear exhaust has.
Fans work by a blade moving through air. Because of the pitch of the blade, this leaves a low pressure area behind it, the byproduct being pressurized air forced away from the front side. So the faster the blade spins, the stronger the low pressure area is.
But, that affects the whole area surrounding the fan, not just a cone like the forced air. As a consequence, that low pressure will attract air from the nearest strongest source, and in the case of a rear exhaust that happens to be the 14.7lbs in² that's coming through the top fan vent hole. To overcome that and have a positive system takes a lot more than what front fans can supply, especially at idle speeds, so you'll find almost all cases with top vents run negative at idle. Having an exhaust at the top rear makes that low pressure area stronger, increasing the pull towards the front of the case.
This works for the gpu too. The gpu draws air in from underneath, creating a low pressure area below it, nearest the fans. Normally this is fed by the front fans with decent static pressure forcing the cfm across that relatively small distance in a direct shot. But many newer closed front designed cases have such lousy air draw characteristics that even with high speed fans, they are not getting enough air fed into them, like spinning in a vacuum doing next to nothing. So only a little air makes it to the gpu. Without that fed air, the gpu will pull air from the pcie slots next to it, and that air is generally cooler than the air from the fans pushing case temp air around. In cases like the nzxt H510, it's been tested and proven the gpu runs cooler without front intake fans, relying solely on what it pulls from the rear.
Having nothing but negative pressure might make for a little more dust, but at low movement rates the air will get pulled through the easiest source first. The big gaping holes where the front intakes are usually, covered with a dust filter.
It's not a new concept, all the original pc cases had nothing but a rear exhaust. The difference now is a far more efficient cpu cooler and a gpu that naturally wants its exhaust to rise.
One of the best airflow cases around is the fractal design meshify C, 3x intakes and 1x measly exhaust. Runs a positive system almost all the time, the 3x fans well over compensating for any distance. As long as the silencer tops are in place, creating basically a tunnel. Remove just one cap and airflow goes in the toilet as the rear now has fresh access directly above, the intakes not having enough.
You can test it out, 3x exhausts vrs 1 exhaust and 2x intakes, but I'm betting you'll get better temps with a negative system.