> Can you provide an explanation for why the WMF has never devoted resources to approach that kind of tools, many times have been requested by the community, and is using them to develop an entirely separate tool based on entirely different principles?
Wikitext structured pages can't provide enough structure to have for example machine readable contents that would allow better interactions (through notifications) or create a sort of inbox for all messages you receive. We are in a loop, I think.
The Teahouse was a test about newcomers retention, not specifically about discussions. One of the aspects was indeed to ease discussions to increase retention, so a specific hack has been created for it. It appears that editors had more success when using the hack that opens windows to reply than regular wikitext. IIRC, it has motivated Flow's kickstart, to create a structured system that would give a more clear interface and more interactions.
> Are you going to include features in Structured Discussions for lightweight structure? (a.k.a. editing the page structure in markup mode). This is huge news! ;-)
Maybe later. We don't know yet. It is a possible option and all options have to be considered. But for this fiscal year, the plans plans are already defined.
> Seriously, "topic move" and "messages move" is less than what is possible in wikitext semi-structured pages; those features only solve a few use cases, but they fall way short from what lightweight structure is being used for in Wikipedia.
Allow me to disagree: if they solve a few use cases, I think they solve most done actions. The majority of interactions done daily in conversations are, I think, 4 types: create a new conversation, reply to someone (just below - regular reply), create a sub-discussion or move the topic to another place. There is of course extended cases, thousands, but they are proportionally a few.
> Can you please create a central repository of community-requested use cases, so that we don't need to repeat them again and again?
In theory, everything has been transferred as product definition on Phabricator or on category:Flow. But there is a lot of things in it and I haven't finished to explore everything.