fair enough. care to explain what would be a different topic archetype example then? It hasn’t been defined somewhere, has it?
Because from how I’d see it, wiki would be about the first post in a topic in almost all cases, aren’t they? Or what case do you see when a collaborative post (that’s how I understand wikis in discourse at the moment) would be on other posts than the first one?
So assuming a wiki therefore is on mainly about the primary post, I’d argue that the other posts are a discussion about it, but you might also want to have this rendered differently with a higher emphasis on the wiki post itself – as this shall be subject of change, reflecting the latest conclusions of that conversation, shall it not? Coming from that perspective, looking at the current system, I’d argue that it falls on the level like the distinction between private message and normal topic. Which is defined by it’s archetype.
If it is just about allowing others to edit a post, I consider the “share edit” plugin a more than sufficient solution – and even for that one I don’t see why you’d do that for a non-primary post in a discussion…