I agree. It’s very important to note that even if the subject was discussed in person at PyCon, the audience for the PEP (and the feature) will include a lot of people who weren’t party to that discussion, and it’s crucial to make sure the PEP requires no familiarity with the discussion.
I’m also very confused because there was an extensive discussion about this here on Discourse, and although that discussion is linked in the proposal, none of the points made there seem to have been incorporated in the proposal (in particular the suggested approach for Jupyter).