On the contrary - you can't prevent intolerance from spreading without a perfect Panopticon police state. That's precisely why Europe is failing at it so badly, despite all their hate speech and extremism laws. Organizations like AfD can dog-whistle in public to avoid crossing legal limits, while still fundamentally communicating the same ideas. You could crack down on that if you had a pervasive surveillance state monitoring all private communication, but they aren't willing to go there.
On the other hand, policing actions is much easier, because the more consequential ones are also the more prominent - you don't need a surveillance state to deal with them, you just need a reaction force.
On the other hand, policing actions is much easier, because the more consequential ones are also the more prominent - you don't need a surveillance state to deal with them, you just need a reaction force.