[FredFredrickson]

I don't understand this logic entirely. If your site is unavailable due to normal, unavoidable probabilities in reasonable uptime, why does it matter if the CDN is hosting your scripts or not? Your site isn't going to be around to access them.

[k3n]

It doesn't matter in those cases; it DOES matter for the 99%+ of the time that both the CDN and your site are working optimally. In theory, the CDN should provide the best all-around experience for users (caching, lower latency, parallel loading, etc.). THIS is why you have the CDN -- not as some fail-safe for when your site goes down.