Title is a complete lie/misleading. They get a license, not ownership. Let's dissect what it actually says, and we do it backwards, because given the discussion around this subject it seems like people space out or have their mind clouded by outrage before they get to the end of the sentence: > help you [do things] as you indicate with your use of Firefox. So this already only covers things that you indicate you want…
I don't believe that dissection is a good way to understand the implications of this clause.
>When you upload or input information through Firefox, you hereby grant us a nonexclusive, royalty-free, worldwide license to use that information to help you navigate, experience, and interact with online content as you indicate with your use of Firefox.
Rather than go over this word-by-word, please tell me: what limits exactly does this place on Mozilla? What rights does it give to the user? One way to express such a limit is by construction, that is, construct hypothetical acts A, B, and C that would be allowed under these terms, but actions D, E, and F would not be allowed (and be a cause for action by a user). I assert that the first set includes literally anything you can imagine (modulo a sophists ability to morph "help you" into anything they want), and the second set is empty.
To steel-man this concept, let us say that Mozilla wants to store and use your password to your bank to check your balance regularly. I assert that this action is allowed by there terms. Why? First, you used Firefox and therefore enabled the clause. Second, your authentication details are entered through Firefox, and this constitutes "input" or "upload", to which they assert ownership (which I will use as shorthand for a "nonexclusive, royalty-free, worldwide license"). One thing they could do with your financial data is show it to you (least harm). Another thing is to aggregate it with other's data (medium harm). Yet another application would be to pool it into a database to be sold to the highest bidder (maximum harm). In the latter case, you could make the argument that such a move "helps you" by giving Mozilla a reliable revenue stream that helps fund continued development of the browser.
Needless to say, I am appalled and feel bad for all the many people I've told about Firefox over the years, described it as a bastion of fairness and privacy in an all too often sinister world. And now that they've assert these extraordinary rights over user data, I feel ashamed of my advocacy. I daresay that even if they rescind this incredible overreach, I will not come back. My trust has been broken and cannot be easily (if ever) repaired.