This is only a temporary “problem”. Eventually, ads will be incorporated into the story, and/or advertising companies will include clauses in their contracts. I imagine those clauses will DEMAND that websites include advertising in AI readers or not get paid for any ads they run.
Think enshittification. AI readers are only ad-free now in order to make them seem like an attractive option, and get people hooked on using them. I bet the numbers have already been calculated and decided on. Once AI readers are used by enough people, the ads will start.