Why do you care how they trained the model? If OAI can train on copyrighted material, then morally, I see no problem with others training on their outputs too.
For what it's worth, even XAI's chatbot referred to itself as being trained by OAI, simply due to the amount of ChatGPT content available on the web.
Because these models aren't the end goal. The end goal is AGI in 5-10 years and these models are measures of each company's ability to move toward that goal. If someone is plagiarizing someone else's model, then that seriously erodes everyone's confidence in that company's ability to be the first to AGI and we stop respecting their models, they receive less funding, etc.
For what it's worth, even XAI's chatbot referred to itself as being trained by OAI, simply due to the amount of ChatGPT content available on the web.