In the neo-noir era, they started off that way too; but at some point, which a scholar may wish to document, the gains became nil. The flashbacks became unneeded complication, confusion, unneeded narrative, an intellectual game. The story-telling has suffered.
Here's an example.
The following snippet is from a movie review of the neo-noir "The Villainess" (2017):
"'The Villainess' doesn’t have a particularly interesting story to tell, a fact it tries to obscure by fracturing that story in any number of uninteresting ways. The chronology is needlessly jumbled from the start so that it becomes difficult to determine where we are at any point in time, or which part of Sook-hee’s life is meant to be her present. It soon becomes downright impossible to care. And if you do bother to figure out how all of the piece fit together, the film rewards your diligence by muddying the waters even further, slipping into the recesses of Sook-hee’s memory in order to crack open her deep-seated daddy issues."
The Korean golden age of neo-noir is probably coming to an end, if this is indicative. Creative periods rarely last very long before imitation and worse set in.