Apple's successes have generally not involved a default position of "free but ad-supported". For example, the iTunes store is a massive success for Apple, but didn't begin with free downloads supported by embedded ads in the music (which is what other music services have done). Instead they said "here it is, $0.99 per track".
Apple's track record of not needing to track me or sell my personal information to prop up its business models, because they launch products that have real "get the end users to pay money for it" business models, is one reason why I stick with their products.
You could still have a free service that displays ads.