Regardless of whether there is value in chat history or not, for some people it is important.

Back in the day during the music streaming wars there were tons of "move your playlists from A to B" services. Streaming services could not hold on to customers because all their playlists were on there.

I'm sure that similar services will pop up for chatbots.

Also, you can always just ask your chatbot to generate a file with your chat history, given that it's all part of the context anyway.