As bad as Democratic politicians are at running cities, they at least have enough institutional knowledge to keep things going, even if they don't run very well. Policing gets done, services are offered, maintenance is performed. They know the levers you pull and buttons to push in the city government machine. The DSA lunatics and the BLM grifters have no clue. The machine would grind to a halt. Of course, when things go to hell in the cities, it would never be their fault. It's going to be blamed on sabotage by racist whiteys. Let the DSA and BLM take over and you'd be looking at dozens of Detroits and white flight that would dwarf the white flight seen in the 60s after those riots.