Because uBlock Origin ships with the default filter lists, so that it can work immediately out of the box without having to remotely fetch these filter lists at

Because uBlock Origin ships with the default filter lists, so that it can work immediately out of the box without having to remotely fetch these filter lists at launch time (updated versions of these lists will be automatically fetched some time after launch). It's not uncommon that the remote servers hosting the lists fail to respond, which would cause the extension to "malfunction" if this happened after first install -- these lists are key for the proper functioning of the extension (at least in its default out-of-the-box settings). I want the extension to work properly immediately after 1st install. The size of uBlock Origin as downloaded from AMO or Chrome store is ~1.5 MB (because it's compressed). The compressed package would be ~650 kB without the 3rd-party lists (the content of these lists are not javascript code).