I don’t think Google does it better. But switching from Chrome to Firefox makes much less sense if Mozilla still performs advertising. And, least be said, fires a CEO for having made a private political donation one day, so it is not politically agnostic either.
You are correct that Mozilla has implemented profile encryption and it is believable. However, NSA has backdoors at every level, so having an account online isn’t really a good practice.
And as far as I know, Mozilla can't access the key that encrypt Firefox profiles (as long as your profile password is not 123456). Didn't check the source code, but I guess that if they weren't doing that for real, someone would have spotted it already.