What part of this exactly do you think is not possible with a standard firefox extension? I don't see anything.
Even if I'm missing something, firefox has a history of creating new APIs to allow extensions to do things that they want done, for instance with the container tabs extension. That, frankly, is the only remotely acceptable way to incorporate branded third party AIs into the browser.
> What part of this exactly do you think is not possible with a standard firefox extension?
I don't know, because I don't know exactly what that functionality does. My comment was really more general: since the plugin system changed, there are quite a lot of things that are no longer possible or are no longer possible in a non-clunky way.
My assumption is that if it could have been done as an extension, it would have been. That the reason they build all these things into the mainline browser is because it's not possible to do them (or do them well enough) as extensions.
> firefox has a history of creating new APIs to allow extensions to do things that they want done
Kinda, but that's a very high friction path that can't be relied on. If the extension system doesn't currently have functionality that is needed to accomplish a thing, there's no point in starting to develop the thing until that functionality is added. That functionality won't be added unless there is a great deal of demand for it to begin with. That leads to a chicken-and-egg situation where there can't be provable demand without an implementation showing people want it, but you can't have an implementation without proving demand enough that Mozilla will bother to support it.
The chicken and egg problem doesn't apply when it's mozilla developing the extension, they can add support for it because they want to add support for it with no proven demand...
Perhaps the problem is that they no longer think that a slim, modular browser is a desirable thing, then. I don't know. All I know is what it looks like from the outside.
Even if I'm missing something, firefox has a history of creating new APIs to allow extensions to do things that they want done, for instance with the container tabs extension. That, frankly, is the only remotely acceptable way to incorporate branded third party AIs into the browser.