So police should ignore all crimes other than murder? Because that’s what you’re going to get…

e.g. nobody will prosecute any property related and others low level crimes (e.g. damage is less than hundreds or at least tens of thousands). Crime rates will increase and the system will collapse at some point.

And what dictator is going to implement this perfect solution?

Here's how things have manifestly played out over the past 150 years: procedural rules are strengthened because citizens are afraid of unjust prosecution. Some high profile bad guys, or parade of run-of-the-mill criminals, get off because of said procedural loopholes, after which voters demand politicians expand substantive criminal law to re-balance the equation. Upon which more unjust prosecutions enter the public consciousness. Wash, rinse, repeat.

This is what systemic injustice looks like, and the cycle continues as unabated as ever. On the one hand, you have movements like BLM, which have indeed effected change even in the most conservatives jurisdictions, largely by changes in procedural rules by courts and in policy by prosecutors and municipalities. At the same time, you have #MeToo, Harvey Weinstein, etc, which has resulted in the expansion of sexual crimes and punishments, and elimination of statutes of limitations, partly because procedural protections have made it extremely difficult to prosecute past behaviors, not because they strictly weren't already cognizable crimes.

Nobody is going to lose sleep over Weinstein, but long-term which demographics will bear the brunt of this tightening of the screws through the substantive law? You see the fundamental contradictory behavior here? There's tremendous overlap between the #MeToo groups and the BLM groups, and for both their demands are premised on empathy and justice, but at the end of the day we're going to end up with a harsher system that will further disproportionately punish some segments of the population over others. That's what systemic racial injustice looks like, yet nowhere can you find ill intentions or a desire to oppress anyone.

There's an alternative path, here. Notice how the legal screws have taken centuries to slowly but inexorably tighten without any concerted effort, yet in less than a single generation the normative behaviors of individual judges and other legal professionals, both as regards defendant rights (BLM) and victims rights (#MeToo) has seen a sea change. That suggests that by giving back more discretion to the system, not less, it's possible and, IMO, much more likely we could end up with a more fair system all around. Not guaranteed, of course, but neither is it guaranteed that just throwing more money and resources at the existing system would, even assuming we could even achieve let alone maintain that degree of attention from society. The difference between these two approaches, though, is that one requires trusting our fellow citizens, while the other holds out the (fantastical) prospect of an engineered solution.