I think for the moment the leading AI companies are strongly incentivized to not succumb to the advertising curse. Their revenue is subscription driven and the competition is ridiculously fierce and immune to collusion. Everyone is trying to one-up everyone else and there is no moat that locks you into a single product. Their incentive is to score as high as possible on benchmarks in order to drive up their user base in order to increase subscriptions. Any time spent on implementing advertising is time their adversaries are spending making their models better. Let’s hope the competition stays fierce so that we don’t get enshitification anytime soon