It's a big leap from thinking there shouldn't be states to undermining them through direct attacks; there aren't many of those, I think. But it is true that security services frequently overstep their boundaries, and that not all countries have proper guarantees during a judicial process, so even innocent anarchists may have something to fear.
In general one of the defining features of a state is a monopoly on legitimate violence. It stands to reason that challenging a state then involves violence, and sees violence used in retribution.