If T33919: Allow posting new sections to top of page on a per-page basis was implemented in MediaWiki core, it would work with the DiscussionTools new topic tool as well – new topics would be added to the top, since we use the same code for saving changes.

There would be some issues with the user interface to resolve separately though (e.g. the new topic form would still appear at the bottom of the page, the posted topic might not be scrolled into view after saving, etc.).

Also asked here: https://www.mediawiki.org/wiki/Topic:X1kmbhpc6kpsa112

On Extension:DiscussionTools page on mw.org this extension is mentioned:
https://www.mediawiki.org/wiki/Extension:PlaceNewSection
Its code is fairly simple, maybe some version of it can be deployed and maintained by DiscussionTools team? I suppose Wikimedia wikis do not need __ADDSECTIONABOVE__, but __ADDSECTIONBELOW__ is basically what we need here.

As an alternative, you can try to provide the ability to sort topics (latest first)? But I think it will affect the page loading speed.

In T313165#9085282, @Iniquity wrote:

As an alternative, you can try to provide the ability to sort topics (latest first)? But I think it will affect the page loading speed.

Sorting could happen on the server side, though it is more complicated. It does seem like the best solution for this sort of thing since it doesn’t require an overhaul to how section=new functions, and it would introduce an old feature from Flow. Ideally, there should be a per-user setting of how a user wants to see threads on the page and per-page setting of how the community wants to see threads on the page.