Except in the case of GPT-x, the facade builder must take extra pains to sanitize the inputs, so it doesn't become just a free GPT account for the user to interact with on unrelated topics. That's much more challenging due to the open nature of the prompts (the selling feature). One really lame solution is to ask the user to use their own openai API key.
If you're forcing your user to get their own OpenAI account, you're pushing them away from your product, at least somewhat. IMO the integration needs to be seamless for the illusion of "we're providing value here, not just wrapping GPT" to hold.
