How does this do anything but validate their concerns? They're not saying "if we train LLMs on their own output, they'll get slower or worse", they're saying "

How does this do anything but validate their concerns? They're not saying "if we train LLMs on their own output, they'll get slower or worse", they're saying "if we train LLMs on their own output, it gets even harder to actually derive sourcing for what they produce."