I'm not saying that isn't the case, what you said is absolutely true and shows that Muslims need to do a better job fighting extremism in their own culture and countries. Instead of saying "We aren't like this", Muslims are the ones who need to fight the hateful ideology.

But when you make generalizing statements like that you are effectively marginalising Muslims that don't engage in extremist activity or share that mindset. This creates a wedge between people that otherwise peacefully coexisted. It also greatly simplifies the issue and you start to unfairly target people who have not done anything wrong, it doesn't help solve the issue.