I’m not arguing with that, it’s basic information theory.

One bit, however, is not “the maximum possible amount” you can gain from an oracular answer to a yes/no question. The OP covers exactly this point re: the “Guess Who?” game.

The start of this comment thread was a complaint that OP is showing more than one bit expected for certain yes/no answers. Not best case, expected.

That's why people are talking about the maximum expected value.