In researching T236828: Unexpected PST effect when saving edits to .js pages that were formerly <nowiki> I turned up the (surprising?) fact that the Translate extension is the *only* user of the ArticlePrepareTextForEdit hook in core, and it only uses it to disable PST on articles in the message namespace.
Now that there are Content subclasses for all sorts of things, is there a better way to do this in modern MediaWiki?
I'd love to deprecate and remove this hook if possible.