Why have these companies not manually engineered out a problem like this by now? Just do a check to make sure links are real. That's pretty unimpressive to me.

There are no fabricated links, references, or quotes, in OpenAI's GPT 4.5 + Deep Research.

It's unfortunate the cost of a Deep Research bespoke white paper is so high. That mode is phenomenal for pre-work domain research. You get an analyst's two week writeup in under 20 minutes, for the low cost of $200/month (though I've seen estimates that white paper cost OpenAI over USD 3000 to produce for you, which explains the monthly limits).

You still need to be a domain expert to make use of this, just as you need to be to make use of an analyst. Both the analyst and Deep Research can generate flawed writeups with similar misunderstandings: mis-synthesizing, misapplication, or missing inclusion of some essential.

Neither analyst nor LLM is a substitute for mastery.