Comment 21 for bug 1952766

Regarding your other question; sandboxing would of course be best but that's something that would need to be designed from the ground up. And then new APIs specifically for sandboxed extensions would be needed. And then we would still find either most extensions want to do things not possible in the sandbox, or most extensions never get ported to the sandbox model. So sandboxing is unlikely to ever happen. More likely that extensions would just be forbidden, but more likely than that is maintaining the status quo - extensions are allowed to do anything and break anything.