I can't speak for all of the members of the upcoming documentation WG, but as someone that will be on it (based on our discussions at the recent core dev sprint), my personal vote would be for keeping it as a comprehensive guide for beginners of Python. Detailed enough that it covers the fundamentals, but skips out on more advanced topics and info that is likely going to be less applicable to most new users.
I would consider __cause__ and __context__ to fall under the category of being "useful to know, but far from essential for beginners". You can have a decent understanding of most python programs without ever knowing about those two dunders. So I would definitely be in favor of removing the mention of __cause__ and not adding __context__, in my opinion it adds extra unneeded complexity.
That being said, I'm not opposed to something like having something like a footnote at the bottom of the section that links to a more advanced topic (maybe an exception how-to?). It should be at the bottom of the section so it doesn't add extra cognitive overhead for those trying to grasp the basics, but allows for those who are interested to get a more in-depth understanding if they want to. I would suggest redirecting the contributor who proposed those changes to working on something like an exception how-to; assuming that's something they're interested in.