Mastodon's handling of Article was done just to piss me off. I filed an issue on Mastodon back in the early days of ActivityPub asking if the complete and total stripping of HTML tags could be relaxed on the Article type - and other software that used HTML would happily use that instead of Note. Eugen resolved the bug by removing the content entirely and turning it into a link. Nope. Can't have any of that nasty HTML on Mastodon; even though that is the default mediaType for ActivityPub.

I will never file another issue on Mastodon, no matter how critical the issue is.  As it exists today, Article has been destroyed for other software to ever use correctly, in the same way that summary and the addressing fields have.