They’re talking windows in general
This goes for both chrome and bing: If a service is free, you are the product.
True for Windows as well. Ever upgraded to a new version before the first SP? Linux just gets upgrades a lot faster than Windows (and I mean the conservative distros like Debian. Bleeding-edge distros are on a completely other level).
Perhaps a better statement would be, if a for profit service is free, you are the product. Obviously it’s possible for someone to make free stuff if they want to, but if someone is making money from you using something, but you aren’t paying them, then they’re making that money by selling someone else access to you.