Not because "it is cool" but because it needs that code to operate. Consider this scenario, even for a classic website/blog: you can eagerly download all of the

Not because "it is cool" but because it needs that code to operate. Consider this scenario, even for a classic website/blog: you can eagerly download all of the textual content at first load as markdown, cache it in the ServiceWorker together with a markdown parser, and go offline. You can then ask the network, if available, only for downloading images that then get added to the offline cache. Even with a spotty and slow mobile connection, after the initial load you are done with the network and you can read all the content in an efficient, environmental friendly and fast way. When the network is available, you can check if there are updates by sending a small request to the server, and update the cache.