I'm pretty sure that the lack of police accountability is a far worse problem, to be honest. It eliminates any chance that we can reform law enforcement to any significant degree.
They are somewhat intertwined though. If police can feed anyone to the DA, and the DA can then use a variety of sketchy tactics (including junk science, but mostly other stuff) to punish them, then it all works. If it kept resulting in cases that get thrown out, the feedback loop would slow it down some.