GP wants a translation service built in to the browser. Even if they appreciate it being local-only, coming back with “no, here’s some largely irrelevant technical difference that makes this better!” misses the point.
This seems to be about the first time I see Mozilla knowing its own users better than a random HN user know Mozilla's users.
Mozilla/Firefox is meant for users who care about privacy, it's literally the first taglines you see when visiting the landing pages for Mozilla or Firefox.
So, with this newfound knowledge about who is using Firefox and who is using other browsers like Google Chrome, maybe now it makes sense why Firefox wanted local translations instead of sending them off somewhere else?