It could absolutely use twice as many dimming zones, in my opinion. But you have to remember this is also still only a 27'' panel.
I don't have any pictures, but i'm pretty sure you can look at some reviews that will show you it. You don't really see the haloing if it isn't a scenario like you describe, whites on top / next to complete black.
this is the reason why Asus release the
PG27UQX with 576 zones.
In any case those monitors are not ready to be marketed, too few zones and fans, really? fans in a monitor?
New Asus PA32UCX have 1150 zones, that is a FALD monitor, not those ones