Once you're down to user interface, you're no longer in "insurmountable technical advantage" territory.

But more critically, chat.openai.com is more of a tech demo than a serious product. So one can optimize the UX for "chatty and engaging" without being too concerned for accuracy. Bing, on the other hand, is intended to be a search product. It's noteworthy that adjusting the same model to provide a more accurate search experience seems to have snuffed out a lot of the magic.