> Well, this post of yours has shown me that the problem is more
> complicated. Because in this case, it was probably the Right Thing :)
> to start a new thread instead of adding this post of yours to the one
> discussing category theory and other nonsense.

One could start a new thread from scratch (with no parent message). But
if the new conversation is an offshoot of the old one, that information
would not be recorded.

> As long as you reply to the most reasonable post, the flat list still
> gets a nice tree structure:
> https://srfi-email.schemers.org/srfi-discuss/threads/2020/06/
>
> But it still allows for newcomers to read through all posts sequentially.
>
> (An unfortunate counter-example is what has happened on the SRFI 177
> lists: I think it is extremely hard for a newcomer to understand the
> timeline of the discussion and, probably, the discussion as well.)

I agree. The big trees can become almost unreadable. Hacker News
(news.ycombinator.com) and similar platforms also organize the comments
into trees, and have the same problem.

I've tried to solve it for email by changing the subject line often.
Even big trees remain surprisingly readable if sub-discussions change
the subject. It's easy to forget to change it but any change is better
than nothing when it comes to readability :)