There is no feature Firefox provides that is more differentiating than ublock origin. As long as pages load and security issues are patched it is the reason to choose Firefox as a browser. What would they prioritize over it?
[1] https://github.com/uBlockOrigin/uBOL-home/wiki/Frequently-as...
While far from being perfect, I find it good enough for keeping things separated, especially when using a desktop/workspace workflow. For example, in workspace/desktop 2 I have a Firefox window opened with the first tab set to "container A", so hitting ctrl-t there opens new tabs with the same container "A", so I'm logged-in for all projects A. In another Firefox window in workspace 3 I work with "business project B" tabs (where I'm logged into different atlassian, github, cloud, gmail, ...)
Then with a Window Manager like i3wm or Sway I set keybinds to jump directly to the window (and workspace), using the mark feature [1]
It's also possible to open websites directly in specific containers so it's flexible. For example on my desktop 8 I have all my AI webchats in "wherever my company pay for it" tabs: `firefox --new-window 'ext+container:name=loggedInPersonnal&url=https://chat.mistral.ai' 'ext+container:name=loggedInBusinessA&url=https://chatgpt.com' 'ext+container:name=loggedInBusinessB&url=https://gemini.google.com' 'ext+container:name=loggedInBusinessB&url=https://claude.ai'`
It's also the only way I found to keep opened multiple chat apps (Teams, Slack, Discord, ...). The alternative electron apps are as resource-hungry, and in my experience never handled multiple accounts well (especially Teams).
[O] https://addons.mozilla.org/en-US/firefox/addon/sticky-window...
In case of the extension manifest, that's probably layered on top of the JS engine which does get attention and scrutiny. It's not like an API needs to be updated. If you'd always do that, nothing would ever be interoperable and we'd likely have a hard time trying to communicate.
The feature that better adblockers need is one callback that's similar to one that's still in V3. It's not difficult to keep if it's your own codebase.