It is massively more discoverable, for one simple reason:
I am very uncomfortable with IDEs that try to do my thinking for me, and I start turning things off on those occasions when I am forced to use them. It would even occur to me to try autocompletion.
There seems to be a clash of generations here, or perhaps a clash of different educational paths.
I agree it is more a clash of learning paths/training. I started out-- with ZERO knowledge-- in 2014 just before Jupyter started to be popular, and the more I have used it (as well as VSCode and Pycharm), the more I have found myself thinking "OH MAN-- if I had had THIS when I was learning, I would have learned so much faster with these code/feature discovery tools".
Notebooks in particular-- more than IDEs, I think-- are changing the way people learn. if I were teaching someone new today, I'd have them use Jupyter right away, probably not the repl.
But I still use the docs a lot too.