Glean is an example of this and they charge $$$/seat which means it is being selectively targeted at specific teams rather than enterprise-wide.
The problem is that companies don't have their data in a state that can accomodate such a layer. And with the death of EDWs and trend to siloed SaaS apps the problem just gets worse every day.
Which is why AI is going to be more like a mini-assistant inside every app you use instead of some god-like agent.