Well, I suppose it's a matter of perspective and debate.
To me, extremism thrives because of lack of law enforcement There are plenty of extremist nuts in Western society, but they mostly keep in their burrows because they know the law will hold them accountable.
Secondly, religious extremism isn't the only driver of lawlessness. Karachi's woes are caused by old fashioned drug lords and gangsters masquerading as politicians. Even if we eliminate wahabi influence from Pakistan, it will do nothing to solve Karachi's problems.
Powerful people will always be able to extert influence, whether it's through money or ideology. Even rich countries like Britain are not immune, as evidenced by Scotland Yard being disgraced in the Murdoch media scandal. It seems to me that the greatest payoff comes from focussing on corruption and law-enforcement, and having a system of public accountability. We must provide an environment of trasnparency where law enforcement can do their job without fear of retribution from powerful overlords.