Or you could be in a situation where you are trying to demo an app to investors, and you find you don't have proper access to wifi. Or your adsl comes down and

Or you could be in a situation where you are trying to demo an app to investors, and you find you don't have proper access to wifi. Or your adsl comes down and you find that over the spotty 3g your app suddenly takes 30s+ just to come up with an error message just due to the google fonts you used. Those two are JUST personal experience in the last 6 months. Last time I brought this up publicly somebody mentioned that most CDN's are blocked in China too. Given my past experience, I can think of no possible benefit that can make the additional fragility introduced in my systems worthwhile. I'm not using CDN's for anything more than the odd jsfiddle in the future.