Grouping the tangential discussion

I’d like to propose a change to how we structure discussions. In brief:

• add a comment flag tangential
• make tangential discussions less visible
• aiming both to provide space for those discussions, and to hide them a bit

Examples where this might apply:

• A technical post on golang generics, and a comment thread on “generics in go yes/no”
• A post announcing a vulnerability in a C program, and a comment thread on “rewrite in rust yes/no”
• Discussing whether a given submission is off-topic or not
• Discussing the wider context around a submission (the go thing is an example, but this could also be pointing out that there might be a hidden agenda, …)
• Plugging related projects, anecdotes (e.g. “by the way, I built something like this recently: here”)

This isn’t just (or even primarily) about hiding those threads. It’s also about providing explicit space for those discussions. E.g. I’d like community members to be able to plug their related projects without wondering whether that’s on-topic. It would be good to be able to question whether an article is on-topic without derailing the on-topic conversation. More generally, there seems to be a clear desire to discuss these tangential topics, and also clear friction with those who’d prefer to focus on the concrete content. I think trying to accommodate both could be helpful.

As to what “make tangential discussions less visible” would mean, two concrete ideas:

1. Add a second separate comment section below the main comment. Top-level comments flagged tangential just get moved there. Nested comments in the top section that are flagged tangential get uprooted and moved there, with a link back to parent.
2. No changes to the comment section. Instead, add a toggle to hide any comments (and their replies) tagged tangential with a user-configurable default (in which case it should probably default to hidden).

One thing to figure out would be how to decide that something is flagged tangential. Two separate tangential flags might work for a start?