> The problem is .. what flows don't need determinism? Search results / recommendation engine / ad targeting ?

That's not the relevant question, because the actual answer to what you asked is "all flows where human judgement is used".

The thing we need to not blindly use current generation AI for is "things where we accept the combination of an untrained (or barely trained) human with no QA".

IMO, the drive to use AI is not only fully automating a lot of things that shouldn't be so, but also revealing how some of them never should have been in the first place. If your human customer support agent makes stuff up and that got your business a penalty fine, you might discipline or fire them; not so easy when it's an AI that replaced a whole call centre in one go, even when the incident frequency is the same.