That is certainly true for the moment, but IMHO that is not really an argument in this case:
Advertisement can simply show me me some advertisement w/o spying on me. (Effectiveness of targeted advertisement is AFAIK highly controversial anyway.)
My operating system does not have to spy on me and my browser certainly not.
Mozillas BS arguments are just the ‘story told’, obviously they want to make money via advertisement and be the man-in-the-middle. I assume it is their legal right to do so and they can pursue the business model they like, but I do not have to like it.
Again, advertisers will simply use this as an additional source of information about users for real time bidding, and not wind down other methods of information gathering, so this is only bad for me w/o any upsides.
Mozilla is showing it is willing to sell it’s user data out this way (and silently do so), what are the next steps, what will happen with the next updates?
… and I happily have donated and will donate/pay money to/for websites and software I like/use and will happily accept business models dying which depend on selling my data out.
One of the main points of using Open Source operating systems and software is, that I have the freedom to use my own hardware the way I like w/o being up-sold or harassed by advertisement.