It's only for small chunks of data, since you have to limit yourself to the tiniest storage medium the browser allow for your replication. E.G: on my browser,

It's only for small chunks of data, since you have to limit yourself to the tiniest storage medium the browser allow for your replication. E.G: on my browser, you can only store 81920 bytes per domain in cookies, so if I want the max redundancy, I have to limit myself to 80ko. Besides, cookies are sent in each request, so I want to limit myself. Let's say you want more, local storage is limited to 10 MB. It's not huge. But the browser doesn't care about the size of the data, only how recent it is. So it may evict yours, even if it's very small, compared to the huge cache of hundred's of MB from the manifest file or the webworker from other open tabs.