It's one thing to turn a foreign country into a police state, when you need to actually be a productive society that simply stops functioning with large scale unrest.
The problem is not direct force of arms, the problem is society needs a vast number of soft targets to continue to operate. If large numbers of people chose to simply take down power lines there is almost nothing the police or military could do. City's water supply pipes are similarly easy to destroy and difficult to replace. Roads are harder to destroy, but easy to prevent most civilian traffic.
I'm not sure whether you're saying that sabotage of infrastructure performed by the populace is a good way to perpetuate unrest in a way that a militarized state can't squash, or whether you're saying that the state can quickly destroy key pieces of infrastructure to cause pain to people who refuse to fall in line. Because both are true, but the latter is far more likely and effective: after all, who wants to destroy the last remaining enablers of their comfort, shelter, and livelihood just to prove a point... and then what?
One only need to look at the city of Flint, whose water pipes continue to deliver lead-laced water to households black and white, but society has largely routed around the damage: we carry on with our lives and ignore it's a problem. It's only a problem for those in Flint.
Meanwhile, the military and police can turn off utilities, blockade towns, enact curfews, and isolate even the flow of information, all without firing a single bullet. This way, pockets of unrest can be abated before they become a movement so pervasive that the military themselves defect.
Except nothing says it's your power line you destroy. The failure is when group A destroys B's infrastructure and group B destroys A's infrastructure but both groups A and B are in the same country.
The gap from tagging aka spray-paint to tossing bricks through windows is tiny. So, yes you can have independent enclaves that are protected, but it's easy to get into no mans land where the police don't come to some and then most areas without a lot of backup.
The problem is not direct force of arms, the problem is society needs a vast number of soft targets to continue to operate. If large numbers of people chose to simply take down power lines there is almost nothing the police or military could do. City's water supply pipes are similarly easy to destroy and difficult to replace. Roads are harder to destroy, but easy to prevent most civilian traffic.