Perhaps the biggest argument I've often made for this is the fact that every single time there is a fucking terrorist attack in the West, it turns out that the perpetrator was known to security services.
While I agree with your sentiment, the corollary to that is just how many people are known to the security services? How many people do they try and recruit? We're turning into East Germany in the 1970s except that we have better technology and we're actually voting the fuckers in.
Those who claim the dead never return to life haven't ever been around here at quitting time.