All directly or indirectly ad-supported business models will sooner or later come to the point of breakage in serving user”s best interests, as the fundamental misalignment of incentives between the business and its users creates a force too strong to contain.
This is entirely driven by a simple fact that in ad-supported businesses users are not the same as the customers.
I advocated several times and will do it again - Firefox should completely embrace a freemium browser business model, align incentives with its users, and attempt to have a second golden age (first was 2005-2010).