1) chatbot are either based on a search engine (so with limited answers) or AI-based (with sometimes totally inaccurate "understanding" or "answers")
2) knowledgebases (and other kindof FAQ) are still really an open problem: wikis are a way to structure informal knowledge but need A LOT of discipline and human... FAQ are generally limited to the 10 most questions
In the end, the best way to provide knowledges right now is the old "website search engine"... but nothing more. And AI has already shown that - even if it LOOK good at first sight - it's not GOOD ENOUGH to be used (wrong answer looking "right" for example)
Moreover: a website embed a structure, so you know what you can search or how to formulate it even if you dont know what you are searching exactly... a chatbot requires you to ask the right question to get the answer you seek, and that's far more challenging for the user !
As an example: try to ask a tax chatbot about how to get family support... and compare it with looking at the website structure (that clearly show that you're not at the right place)