For the kind of discussions we have on HN (the insightful, informative ones), text is by far the best format. Both in terms of expressiveness and ease-of-consumption. The asynchronous nature of text comments give people time to think before responding.
I'd classify audio discussions (such as those on Clubhouse) more as entertainment, than informative.
I absolutely agree with your first paragraph, but regarding the second the low bandwidth on text compared to audio sometimes means a lot of information is left out.
A lot of times when discussing something here (or anywhere in text) I see something I'm fairly convinced is wrong, but it's apparent that it's misunderstood many steps back, and I just don't bother if I'm not up for writing a wall of text of premise before getting to how that leads to my point.
(And I'm sure vice versa is true equally often)
Audio really helps here, but it's less searchable and accessible post facto, and it requires simultaneous presence.
This format (written) is also super convenient to return to HN and search for something. As long as there is not transcription (at least for searching purposes), audio is semi-useless (at least for the use that I may have).
I have used the 'Search' in HN multiple times to educate myself on topics, reading the article in 3-4mins and then spending 20mins on comment section to expand and enhance my knowledge and/or critical thinking.
I'd classify audio discussions (such as those on Clubhouse) more as entertainment, than informative.