Because normal Cache-Control is only aimed at reducing the amount of data transferred. With newer immutable Cache-Control[0], a CDN going down wouldn't have an

Because normal Cache-Control is only aimed at reducing the amount of data transferred. With newer immutable Cache-Control[0], a CDN going down wouldn't have an effect if you have the resources cached. [0]: https://hacks.mozilla.org/2017/01/using-immutable-caching-to-speed-up-the-web/ https://hacks.mozilla.org/2017/01/using-immutable-caching-to...