1. Cost: it's much easier to build and serve a traditional search index for questions/answers at scale
2. Speed
3. Quality: with search engines you don't just get one answer (you get a spectrum of answers). You have access to the "source" of those answers, which often include additional data that can help you choose the most appropriate solution to a problem.
In this specific case, the "horse" is the LLM - and the "car" is the traditional search engine with modern indexing technologies. But please, don't let simple textbook facts about technology take you off your trip.
But LLM can already do things Google can't.
LLM is not just a search engine.
It's an explainer, rubber duck etc.
Instead of 'google define x' I just say ' explain x' in my dialog with the machine.
And it will only become better and better.
I can also use a horse to ride to my parents and im still using a car?!