Hmm, the reply tool was made opt-out on dewiki in T294591: Config change: Deploy Reply Tool as opt-out preference at de.wiki, tagging Editing-team to have a look.

But this contradicts the mention in the link stated above: https://www.mediawiki.org/wiki/Talk_pages_project/Replying#30_September_2021

The only compromise would be an opt-in instead of an opt-out, (but also without agreement).

I enabled the reply tool on German Wikipedia on Monday, it was an intentional change and not a mistake (T294591).

@doctaxon It was noted in your link on 30 September that "In the coming weeks, we will start conversations with volunteers at the wikis listed above about the prospect of offering the Reply Tool as an on-by default feature there as well".

The conversation happened at https://de.wikipedia.org/wiki/Wikipedia_Diskussion:Kurier#neue_Antworten-Funktion (starting on 21 October) and as far as I can tell (relying on automated translation), the comments there were all positive.

We're also watching the new discussion at https://de.wikipedia.org/wiki/Wikipedia:Fragen_zur_Wikipedia#"Antworten" which began after the config change, and where, as far as I can tell, the comments are also largely positive (although a few people are reporting problems that I'll need more time to understand, since I don't speak German).