OpenAI could also train their models against this easily, making it hard to get at the prompt. Yet, it's super easy, try it yourself:

https://chat.openai.com/share/94455782-5985-4b20-82fa-521f40...

I imagine OpenAI has no problem this, there are no secrets in the prompt, and it may be useful for prompt engineering. If it's harmless, no point in stopping the user from seeing it.