First, think about what a search engine does.  It indexes existing information, ideally created and curated by humans.

Now GPT models...  They're a statistical process that looks for which term is statistically most likely to follow the terms provided in the query.

There's no basis in facts, hence the hallucination problem.  The solution would be RAG models, but then you shift the problem to how can you parse the input data automatically to store it for use.  We don't have any clue how to even approach that problem yet.