Add First Party Support for AdBlock Plus-Style Blocklists in Gecko/GeckoView

This sounds like a good idea, but I'm annoyed that the bug conflates "AdBlock Plus-style lists" with "ad blocking". AdBlock Plus lists are useful in blocking arbitrary unwanted content; for example, I block DuckDuckGo's stuff on its homepage below the search bar. Having support for full AdBlock Plus lists (essentially allowing something like uBlock in the browser itself) would do much to allow for powerful blocking while still having the performance advantages of Manifestv3/Content Blocker filtering. Associating it with ad blocking, especially if there will be default "ad block" lists included, complicates this issue unnecessarily.

Blocklists supported by the browser would be a good idea, but what makes Firefox with uBlock Origin more powerful than Safari with a blocklist (and no uBlock Origin anymore) is that you can’t remove annoyances easily or block certain elements quickly. One could argue that this feature is not used by many average users, but Firefox hasn’t been the browser of the average user for a long time. So it’s all the more important that it doesn’t ignore its evangelists and power users.

There is a place for browser native blocklists. There is still a worthy and much needed place for uBlock Origin in that world. An API where an extension could tell the browser to remember what elements to block (not just URLs) could help. But this is probably better implemented by absorbing, into the browser, (some or most of) the work that uBlock Origin has done.

This bug is a year old, and Firefox Preview / Fenix has in the meantime gained support for uBlock. Considering that's mentioned as motivation for native support, I'm not sure this is still planned?