Problem: On several wiki, the archives of community discussions are structured as "Commons:Village pump/ArchiveYYYY/MM" (this is an example with Commons but this is the same idea on other projects and languages). Not talking about archives, some community discussions are stuctured this way: "Wiktionnaire:Questions_techniques/MM_YYYY" which means there is a new page to watch each month. This leads to the creation of such list.
Who would benefit: every contributor who watch community discussion pages that use subpages. It will allow to see a change in an archived discussion.
Proposed solution: Mediawiki should offer a new button next to the "Watch this page" button. This new button would be "Watch this page and all subpages". Clicking on such button, if a contributor chooses to watch Wiki:XXX, then all subpages are automatically added to the watchlist Wiki:XXXX/aaa, Wiki:XXXX/bbb, Wiki:XXXX/cccc, ... When one subpage is created, it is automatically added to the watchlist of user who watch this main page.
More comments: I think one should allow users to be able to remove subpages individually from their watchlists. For exemple, if one watches Wiki:XXXX, then Wiki:XXXX/aaa and Wiki:XXXX/bbbb are automatically added to the watchlist. Yet, one should be able to remove manually Wiki:XXXX/aaa.
+1. For several months, everybody is forced to copy-paste a page list from a Lua module: wikt:fr:Modèle:Communauté, on the most part of the wikis I know... That's not ergonomic at all. But the best solution would be to also provide these subpages into the same RSS flux. JackPotte (talk) 15:04, 2 November 2018 (UTC)[reply]
I would prefer a per-page option: "Watch this page" and "Watch this page and all subpages" as separate options. The latter won't be changed often, it can be a bit more hidden (like a separate list you can edit). --mfb (talk) 03:27, 4 November 2018 (UTC)[reply]