Probably what happened, is that in doing so, they had to scale either the model size or the training cost to untenable levels.
In my experience, LLMs really suck at fluid knowledge retrieval tasks, like book recommendation - I asked GPT4 to recommend me some SF novels with certain characteristics, and what it spat out was a mix of stuff that didn't really match, and stuff that was really reaching - when I asked the same question on Reddit, all the answers were relevant and on point - so I guess there's still something humans are good for.
Which is a shame, because I'm pretty sure relevant product recommendation is a many billion dollar business - after all that's what Google has built it's empire on.