They've simply run out of data to use to fabricate legitimate-looking guesses. They can't create anything that doesn't already exist.
replies(7):
Why do you think "they" have run out of data? First, to be clear, who do you mean by "they"? The world is filled with information sources (data aggregators for example), each available to some degree for some cost.
Don't forget to include data that humans provide while interacting with chatbots.