Hello @many-toddler-31747, That is an excellent question.
Here are a few pieces to consider. For just QNAs, meaning your bot does nothing but answer questions with a single node in Botpress, Your advantage is limited to the potential of recording the information disseminated by the bot in tables, which means you would have instant access to the chat history if you choose to store it in the tables.
Based on your description above, it sounds like you have some workflows and things you wish to accomplish that is more than just answering basic questions. These workflows and their potential are where Botpress shines. You can build specific workflows, call APIs, and integrate with other services, including OpenAI, to do something with your bot beyond regurgitating information.
The workflows give you complete control over exactly what actions are taken. If a precise response needs to be provided, you can dictate with the text card rather than hoping that OpenAi pulls the exact phrase you need. The best part in such a case is that you don't have to query OpenAi to create that; instead, you can just code it to speed up the response time and save yourself money.
The overarching purpose of Botpress is to provide a user-friendly interface that allows you to harness tools and technologies to craft a journey for your users, and gather meaningful data about that journey. OpenAi can be essential in that journey, but it is only a single piece.
I hope this helps.