How else are they to monetize text outputs? This was always the plan and it's going to get much worse (or better depending on which side of the fence you're on). Google did the same thing when it controlled web indexation: ads, sponsored results and SEO. All of these things will be coming to agents: you will be monetized or you will be paying not to be.
Sam Altman famously said in 2024 "I kind of think of ads as a last resort for us for a business model." So perhaps we could ask him first what his other plans were and why they didn't work.